THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


ACHIEVEMENTS 
IN    ENGINEERING 

DURING  THE  LAS?  HALF  CENTURT 


BY 

L.  F.  VERNON-HARCOURT 

M.A.,  M.  INST.  C.  E., 

AUTHOR  OF  '  RIVERS  AND  CANALS,'  AND  '  HARBOURS  AND  DOCKS. 


With  Illustrations  and  Diagrams 


NEW  YORK 

CHARLES  SCRIBNER'S  SONS 

743-745  BROADWAY 

1891 


/  ni 


PREFACE 


MY  endeavour  in  this  book  has  been  to  describe  briefly 
some  of  the  principal  engineering  works  carried  out,  at 
home  and  abroad,  within  the  last  fifty  years,  avoiding 
technical  phraseology  as  far  as  possible,  so  that  the 
descriptions  may  be  perfectly  intelligible  to  the  general 
reader,  and,  at  the  same  time,  introducing  various  details 
and  comparisons  which  may  interest  engineers  as  well. 
As  the  chief  engineering  triumphs  have  been  accom- 
plished in  the  last  half  century,  there  has  been  no  lack 
of  materials ;  and  some  branches  of  engineering  have 
necessarily  been  passed  over,  as  indicated  in  the  con- 
cluding remarks  at  the  end  of  the  book.  I  trust,  how- 
ever, that  an  adequate  variety  of  engineering  works  of 
great  magnitude,  difficulty,  and  importance  have  been 
described,  to  justify  the  view  that  engineers,  in  direct- 
ing the  forces  of  nature  to  the  use  and  convenience  of 
man,  are  amongst  the  greatest  benefactors  of  mankind. 

Various  details  about  several  of  the  works  described 
have  been  gleaned  from  papers  in  the  Minutes  of  Pro- 
ceedings of  the  Institution  of  Civil  Engineers ;  some 
particulars  relating  to  the  Hudson  Tunne  works  have 
been  obtained  from  *  Tunnelling  under  the  Hudson 


iv  Preface. 

River/  by  S.  D.  V.  Barr ;  about  the  Severn  Tunnel 
from  the  late  Mr  T.  A.  Walker's  book  ;  and  about  the 
Forth  Bridge  from  Engineering ;  and  information  about 
American  bridges  and  works  has  been  gathered  from 
the  Transactions  of  the  American  Society  of  Engineers. 

I  am  indebted  to  Mr  G.  F.  Deacon,  the  Liverpool 
engineer  of  the  Vyrnwy  works,  for  particulars  about 
those  works,  for  affording  me  an  opportunity  of  inspect- 
ing them,  and  also  for  a  photograph  of  the  dam  and 
lake  from  which  the  illustration  in  the  book  has  been 
produced.  The  view  of  the  Manchester  Ship  Canal 
works,  at  Eastham,  is  from  a  photograph  given  me  by 
Mr  Leader  Williams,  the  engineer  -  in  -  chief  of  the 
canal ;  the  Tower  Bridge  illustration  is  from  an  en- 
graving furnished  me  by  Mr  J.  W.  Barry,  the  engineer 
of  the  bridge  ;  and  the  Louviere  Lift  is  from  a  photo- 
graph by  Mr  Lyonel  Clark,  of  Messrs  Clark  &  Standfield 
who  carried  out  the  work.  The  view  of  the  Eddystone 
Lighthouse  is  reproduced,  by  permission,  from  an  illus- 
tration accompanying  Mr  W.  T.  Douglass's  paper  on 
4  The  New  Eddystone  Lighthouse,'  in  the  Minutes  of 
Proceedings  of  the  Institution  of  Civil  Engineers ;  and 
the  engraving  on  page  164,  illustrating  the  blasting 
operations  at  Hell  Gate,  New  York,  is  taken  from  the 
plate  accompanying  my  paper  on  that  subject  in  the 
same  Minutes  of  Proceedings.  Three  of  the  sections  of 
American  railways  in  the  diagram  on  page  30,  and  the 
diagram  of  the  switchbacks  on  the  Oroya  Railway,  were 
obtained  from  •'  The  Economic  Theory  of  the  Location 
of  Railways'  by  A.  M.  Wellington,  a  book  containing 
a  considerable  amount  of  information  on  American  rail- 
way practice. 

The  name  of  Robert  Stephenson,  whose  portrait  ap- 


Preface.  v 

pears  on  the  frontispiece,  will  ever  be  associated  with 
the  development  of  railways  ;  and  though  his  labours 
were  terminated  by  his  untimely  death  in  1859,  before 
attaining  the  age  of  fifty-six,  and  thus  are  only  identified 
with  the  earlier  portion  of  the  period  covered  by  the 
book,  he  was  the  pioneer,  in  the  Britannia  Bridge,  of 
the  system  of  long  span  girder  bridges,  which  has  since 
received  such  a  marvellous  extension.  In  a  book  describ- 
ing engineering  works,  I  have  deemed  it  preferable  to 
devote  the  limited  illustrations  to  the  works  of  engineers 
of  recent  times,  rather  than '  to '  portraits  of  living  en- 
gineers, otherwise  many  honoured  names  should  have 
found  a  place  amongst  its  pages.  Amongst  the  eminent 
engineers  whose  works  have  been  recorded  in  the  follow- 
ing pages  may  be  mentioned  Sir  John  Hawkshaw,  the 
engineer-in-chief  of  the  Severn  Tunnel  and  of  the 
Amsterdam  Ship  Canal ;  Sir  John  Fowler  and  Sir 
Benjamin  Baker,  the  engineers  of  the  Forth  Bridge,  and 
the  former  the  engineer  of  the  Metropolitan  Railway  ; 
Sir  James  Brunlees  and  Sir  Douglas  Fox,  the  engineers- 
in-chief  of  the  Mersey  Railway ;  the  late  Captain  Eads, 
engineer  of  the  St  Louis  Bridge  and  of  the  Mississippi 
Delta  works ;  General  Newton,  engineer  of  the  Hell 
Gate  Improvement  works ;  Mr  G.  F.  Lyster,  the  en- 
gineer-in-chief to  the  Mersey  Docks  and  Harbour  Board  ; 
Sir  John  Coode,  the  engineer  of  Table  Bay  and  Colombo 
harbours  ;  Sir  Charles  Hartley,  engineer  of  the  Danube 
Delta  works  ;  Voisin  Bey,  the  engineer-in-chief  of  the 
Suez  Canal  works ;  the  late  Mr  J.  F.  Bateman,  the 
engineer  of  the  Manchester  Waterworks  ;  Mr  Thomas 
Hawksley,  the  engineer-in-chief  formerly  of  the  Vyrnwy 
Reservoir  works  ;  and  Sir  James  Douglass,  the  engineer- 
in-chief  of  the  new  Eddystone  Lighthouse. 


vi  Preface. 

If  this  book  should  succeed  in  stimulating,  and  also 
to  some  extent  in  satisfying,  the  interest  felt  by  most 
persons  in  large  engineering  works,  and  should  lead  to 
a  due  appreciation  of  the  principles  on  which  such  works 
are  designed,  the  methods  by  which  they  are  carried 
out,  and  the  difficulties  experienced  in  their  construction, 
and,  moreover,  if  the  book  should  establish  the  claim  of 
these  works  to  be  classed  amongst  the  '  events  of  our  own 
time,'  the  objects  aimed  at  will  be  accomplished. 

L.  F.  VERNON-HARCOURT. 


6  QUEEN  ANNE'S  GATE, 

WESTMINSTER, 

iQth  March  1891. 


CONTENTS 


-THE   LONDON    METROPOLITAN    RAILWAYS,  AND   THE 

NEW  YORK  ELEVATED  RAILWAY,  ...  I 

-RAILWAYS   ACROSS    THE    ALPS,    THE   ROCKY    MOUN- 
TAINS, AND  THE  ANDES,  .  .  .25 
-NARROW    GAUGE,    FELL,    RIGI,     PILATUS,    AND     ABT 

MOUNTAIN  RAILWAYS,       .  .  .  .54 

-PIERCING  THE  ALPS,  .  .  .  .70 

. THE     DETROIT,      HUDSON,     MERSEY,      AND     SEVERN 

TUNNELS,     THE      THAMES      SUBWAYS,     AND     THE 
SARNIA  TUNNEL,  .  .  .  .85 

VI. — THE  PROGRESS  AND  PRINCIPLES  OF  MODERN  BRIDGE 

CONSTRUCTION,   .  .  .  .  .112 

VII. — THE  HAWKESBURY,    ST    LOUIS,    GARABIT,    HOOGHLY, 

BROOKLYN,  FORTH,  AND  TOWER  BRIDGES,  .          132 

VIII. SUBMARINE  MINING  AND  BLASTING,  .  .          159 

IX. — THE     PORTS     OF     LONDON,     LIVERPOOL,     ANTWERP, 

MARSEILLES,  AND  NEW  YORK,        .  .  .172 

X. THE    BREAKWATERS    OF    TABLE    BAY,    ALEXANDRIA, 

BOULOGNE,     COLOMBO,     DOVER,    AND    NEWHAVEN 
HARBOURS,  .  .  .  .  .189 

XI. IMPROVEMENT    WORKS    ON    THE    TYNE,    THE    SEINE, 

THE  MAAS,  THE  DANUBE,  AND  THE  MISSISSIPPI,    .          206 
XII. — THE    WEIRS     OF     POSES     ON     THE     SEINE,     AND     OF 
CHARLOTTENBURG     ON    THE     SPREE;     AND    THE 
HYDRAULIC  CANAL  LIFT  OF  LA  LOUVIERE,  .          224 

XIII. THE  AMSTERDAM  SHIP  CANAL,  AND  THE  MANCHESTER 

SHIP  CANAL,          .  .  .  .  .238 

XIV. — THE    SUEZ,     PANAMA,     NICARAGUA,     AND     CORINTH 

CANALS,  .....         253 

XV. — THE  MANCHESTER  WATERWORKS,  AND  THE  VYRNWY 

DAM  AND  LAKE,    .  .  .  .270 

XVI. — THE     EDDYSTONE     LIGHTHOUSE,     AND     THE     EIFFEL 

TOWER,  ......          286 


LIST  OF  ILLUSTRATIONS  AND  DIAGRAMS, 


PAGE 

PORTRAIT  OF  ROBERT  STEPHENSON,  ......  Front. 

NEW  YORK  ELEVATED  RAILWAYS, 1 8 

RAILWAYS  ACROSS  THE  ALPS,  ROCKY  MOUNTAINS,  AND  ANDES,            .  30 

ST  GOTHARD  RAILWAY,  LOOPS  AND  SPIRALS,      .            .            .            .            .  35 

OROYA  RAILWAY,  PERU,  SWITCHBACKS  AND  LOOPS,  ....  48 

RIGI  MOUNTAIN  RAILWAY, 64 

MERSEY  AND  SEVERN  TUNNELS,           .            .            .            .            .            .            .  96 

BRIDGES  WITH  LONG  SPANS, 134 

BROOKLYN  BRIDGE, 144 

THE  FORTH  BRIDGE,            .........  148 

THE  TOWER  BRIDGE, 154 

BLASTING  OPERATIONS  AT  HELL  GATE,  NEW  YORK,  .  .  .  .164 

EXPLOSION  OF  MIDDLE  REEF,  NEW  YORK,            .            .            .            .  1 70 

SECTIONS  OF  BREAKWATERS, 192 

RIVER  IMPROVEMENTS,      .........  2O8 

DRUM  WEIR  ON  THE  SPREE,        ........  232 

HYDRAULIC  CANAL  LIFT  AT  LA  LOUVIERE, 236 

SHIP  CANALS, 242 

THE  MANCHESTER  SHIP  CANAL  WORKS,      .             .....  246 

THE  SUEZ  CANAL, 256 

VYRNWY  DAM  AND  LAKE,           ........  280 

THE  EDDYSTONE  LIGHTHOUSE,   1882,          ......  290 

THE  EIFFEL  TOWER, 298 


The  Portrait  oj  Mr  Robert  Stephenson  is  engraved  by  permission 
of  Messrs  Henry  Graves  &•>  Co. 


Achievements  in  Engineering 


CHAPTER    I. 

THE    LONDON    METROPOLITAN    RAILWAYS,   AND   THE 
NEW  YORK   ELEVATED   RAILWAYS. 

PROBABLY  no  better  concise  description  of  the  most 
marked  features  of  the  present  time  could  be  given 
than  the  passage  which  occurs  in  the  Book  of  Daniel, 
relating  to  the  latter  days,  namely,  *  many  shall  run 
to  and  fro,  and  knowledge  shall  be  increased.'  The 
development  of  railways,  and  the  facilities  thus  afforded 
for  locomotion,  together  with  the  extension  of  educa- 
tion and  trade,  have  given  a  great  impulse  to  traffic 
in  large  cities,  and  especially  in  London.  With  a  rapid 
growth  of  population  in  the  metropolis,  and  constantly 
increasing  requirements,  the  traffic  in  the  most  im- 
portant thoroughfares  necessarily  largely  augments  ; 
whilst  little  can  be  done  to  relieve  the  excessive  traffic 
along  the  main  streets,  beyond  a  few  new  roads,  con- 
structed at  enormous  expense.  Accordingly,  schemes 
were  naturally  started,  about  the  middle  of  this  century, 
for  enlarging  and  facilitating  the  means  of  communi- 
cation, without  encountering  the  delays  and  increasing 
the  congestion  of  traffic  in  the  principal  thoroughfares, 

A 


1  Extension  of  Railways  in  London. 

The  growth  of  the  metropolitan  traffic,  moreover,  is  not 
merely  measured  by  the  increase  of  population  in  the 
ever-extending  area  of  London  itself ;  but  the  very  large 
number  of  persons  who  now  reside  in  the  suburbs 
and  neighbouring  country  districts,  and  come  regularly 
into  London  for  their  day's  work,  have  to  be  con- 
sidered. It  is  of  importance  for  this  suburban  popula- 
tion, and  for  travellers  from  a  distance,  that  they  should 
be  able  readily  to  get  from  the  railway  stations  to  their 
places  of  business,  and  from  one  terminus  to  another. 
Increased  facilities  of  access  have  been  provided  by 
doubling  the  lines  of  way  of  all  the  principal  railways 
running  into  London,  and  by  extending  the  lines  in 
some  instances  further  into  the  heart  of  the  metropolis ; 
such  as  the  extension  of  the  railways,  terminating  at 
Battersea,  to  Victoria  Station  in  1860  ;  the  extension 
of  the  South-Eastern  Railway  from  London  Bridge 
to  Charing  Cross  and  Cannon  Street,  constructed  be- 
tween 1860  and  1866  ;  the  London,  Chatham,  and 
Dover  Railway  extension,  from  Ludgate  Hill  to  the 
Holborn  Viaduct,  about  1873;  and  the  Great  Eastern 
Railway  extension,  from  Shoreditch  to  Liverpool  Street, 
opened  in  1875.  Some  idea  of  the  great  development 
of  railways  within  the  metropolis  in  the  last  thirty-five 
years  may  be  gathered  from  the  consideration  that, 
whereas  no  railway  bridge  crossed  the  river  Thames 
within  the  metropolitan  area  before  1860,  there  are  now 
four  railway  bridges  over  the  river  below  Chelsea, 
namely,  at  Pimlico,  Charing  Cross,  Blackfriars,  and 
Cannon  Street,  which  have  been  all  doubled  in  width 
since  their  erection.  Moreover,  trains  now  pass  unseen 
through  the  world-famed  Thames  Tunnel,~opposite  the 
London  Docks,  completed  in  1843,  an^  purchased  about 


Commencement  of  Underground  Railway.        3 

twenty-five   years    later    by  the    East    London    Railway 
Company  to  enable  them  to  cross  the  river. 

UNDERGROUND   METROPOLITAN   RAILWAYS. 

As  early  as  1834,  steam  carriages  were  run  along  the 
Marylebone  Road  for  conveying  passengers  between 
Paddington  and  Moorgate  Street;  and  in  1837  the  ques- 
tion of  the  improvement  of  railway  communication  in 
the  metropolis  was  brought  forward.  The  steam  carri- 
ages could  only  carry  a  few  persons ;  and  the  tramways, 
laid  down  subsequently  in  various  parts  of  London, 
whilst  affording  a  comfortable  means  of  locomotion,  can 
only  be  placed  along  the  less  frequented  wide  thorough- 
fares, and,  like  ordinary  omnibuses,  tend  more  or  less 
to  impede  the  general  traffic  in  the  streets.  In  1845, 
nineteen  Bills  were  presented  to  Parliament  for  con- 
structing railways  in  the  metropolis,  one  of  them 
consisting  of  a  scheme  for  a  general  central  station, 
an  idea  which  has  since  been  successfully  carried  out 
in  some  towns  of  more  moderate  size.  At  last,  in  1854, 
an  Act  was  obtained  for  constructing  an  underground 
railway  from  Paddington  to  Farringdon  Street ;  but, 
owing  to  difficulties  in  raising  the  necessary  capital, 
the  works  were  not  begun  till  1860.  This  first  section 
of  the  Metropolitan  Railway  was  opened  early  in  1863; 
the  first  portion  of  the  District  Railway  between  Ken- 
sington  and  Westminster  was  opened  at  the  end  of 
1868,  and  extended  to  Mansion  House  Station  in  1871  ; 
and,  finally,  the  completion  of  the  *  Inner  Circle,5  from 
Mansion  House  to  Aldgate,  was  effected  in  1884.  The 
Underground  Railway  is  termed  the  'Inner  Circle/  to 
distinguish  it  from  the  outer  circle  of  railways  with 
which  it  is  in  connection,  going  round  by  Addison 


4  Advantages  of  Underground  Railway. 

Road,~Willesden,  Chalk  Farm,  Broad  Street,  the  Thames 
Tunnel,  New  Cross,  and  Clapham  Junction,  which  latter 
railways  both  connect  the  outlying  portions  of  the  vari- 
ous linevs  converging  to  the  metropolis  and  serve  the 
suburbs  encircling  London.  The  Inner  Circle,  however, 
is  not  really  circular  in  form,  for  it  is  an  irregular  oval, 

5  miles  long  from  east  to  west  and   if  miles  wide  from 
north  to  south  ;  and  its  shape  suggests  the  idea  that  a 
railway  cutting  across  the  narrow  central  portion  of  the 
oval,   say   from  Victoria,  or   Charing   Cross   stations,   to 
Baker  Street,  Portland  Road,  or   Gower  Street  stations, 
would  be  a  distinct  gain  to  the  public,  though  probably 
not  to    the  shareholders    of  the    metropolitan    railways. 
This  shorter  diameter,  however,  of  the  oval  is  traversed 
by  omnibuses  in  connection  with  the  railways. 

The  advantages  of  an  underground  railway  in  a 
city  are  that  it  does  not  occupy  any  of  the  surface 
area ;  that  it  is  hidden  from  view,  and  therefore  pre- 
sents no  unsightliness  or  cause  of  discomfort  in  the 
neighbourhood  of  important  buildings  and  main  thorough- 
fares j1  that  the  purchase  of  land  is  avoided  when  it 
passes  along  under  the  line  of  a  road,  or  in  tunnel ; 
and  that  it  does  not  cause  any  interference  with  the 
roads  and  railways  which  it  traverses  in  its  under- 
ground course.  On  the  other  hand,  such  a  railway 
necessitates  the  construction  of  an  almost  continuous 
covered  way,  resembling  a  succession  of  tunnels, 
through  which  trains  have  to  run  in  the  dark,  and 
the  ventilation  of  which  is  more  or  less  imperfect. 
Buildings,  also,  have  to  be  underpinned  or  pulled 

1  Authority  could  certainly  not  have  been  obtained  for  the  construction 
of  a  railway  on  a  viaduct  in  front  of  Westminster  Abbey,  or  along  the  Thames 
Embankment,  in  the  line  followed  by  the  District  Railway. 


Construction  of  Underground  Railway.          5 

down  along  the  line  of  the  railway ;  the  diversion  of 
the  gas  and  water  mains,  intersected  by  the  excava- 
tions, has  to  be  effected  ;  and  pumping  has  to  be  re- 
sorted to  for  keeping  the  low-lying  works  free  from 
water  during  construction,  and  for  draining  the  line 
after  completion. 

Persons  travelling  in  the  Underground  Railway  might 
very  naturally  imagine  that  the  greater  part  of  the  rail- 
way had  been  made  by  tunnelling,  just  as  high  ridges 
are  pierced  by  railways  in  tunnels,  such  as  the  Box, 
Merstham,  Sydenham,  and  other  well-known  tunnels. 
The  depth,  however,  selected  for  the  railway,  below 
the  surface  of  the  ground,  was  not  sufficient  for  the 
adoption  of  this  method  of  construction,  except  in 
two  places,  namely,  between  King's  Cross  and  Farringdon 
Street,  where  a  tunnel,  728  yards  in  length,  was  driven 
under  Clerkenwell,  and  between  High  Street,  Kensing- 
ton, and  Notting  Hill  Gate,  where  a  tunnel  was  made 
under  Campden  Hill  for  a  length  of  421  yards.  The 
rest  of  the  covered  way  was  constructed  on  what  is 
termed  the  *  cut  and  cover '  principle ;  for  the  ground 
was  excavated  from  the  top  to  the  requisite  depth,  and 
the  side  walls,  inverted  arch  at  the  bottom,  and  arch 
overhead  were  then  built,  and  covered  over  at  the  top 
with  earth  again,  thus  forming  a  sort  of  continuous 
arched  bridge  under  ground.  Where  the  line  runs  along 
under  the  streets,  the  roadway  had  to  be  kept  open  for 
traffic,  which  was  accomplished  by  forming  a  temporary 
road  over  the  excavations,  with  planking  laid  upon  cross 
beams  of  timber  spanning  the  opening.  In  some  cases, 
houses  along  the  line  of  the  railway  were  pulled  down,  and 
subsequently  rebuilt  over  the  arch  of  the  covered  way; 
in  other  cases,  the  houses  were  left  standing,  and  were 


6  Precautions  taken  in  Excavations. 

supported  on  a  framework  of  main  and  cross  iron  girders 
inserted  under  the  walls,  the  main  girders  resting  upon 
the  side  walls  of  the  railway.  In  some  of  these  houses 
a  timber  floor  alone  intervenes  between  the  railway 
and  the  kitchen ;  whilst  in  others,  small  brick  arches 
have  been  built  between  the  girders,  and  support  the 
floor.  Considering  the  distinctly  perceptible  vibration 
which  is  felt  even  at  some  distance  from  the  Under- 
ground Railway,  houses  standing  directly  over  the 
covered  way  can  hardly  be  regarded  as  very  quiet  and 
desirable  residences,  especially  where  a  timber  floor  is 
supposed  to  afford  an  adequate  safeguard  against  the 
rattle  of  the  constantly  passing  trains.  Nevertheless, 
habit  has  a  marvellous  influence  in  rendering  people 
unconscious  of  frequently  recurring  sounds,  so  that 
noises  which  jar  upon  the  nerves  of  a  casual  visitor  pass 
unnoticed  by  the  regular  inmate,  who  is  more  than 
compensated  for  apparent  discomfort  by  a  reduced  rent. 
The  excavations  were  in  every  instance  carried  out 
in  very  short  lengths,  of  about  4  to  6  feet,  strongly 
strutted  across  with  timber,  and  rapidly  followed  by 
the  permanent  brickwork  of  the  retaining  walls,  so  as 
to  avoid  the  inevitable  movement  of  the  ground,  and 
consequent  damage  to  adjacent  property  by  settlement, 
which  results  when  any  large  excavation  is  made  in 
the  neighbourhood  of  buildings.  Underpinning,  which 
consists  in  carrying  foundations  down  to  a  lower  level 
by  building  underneath  them  into  firm  ground  not  liable 
to  be  disturbed  by  the  excavations,  has  also  to  be 
effected  with  the  greatest  care,  and  in  short  pieces,  so 
that  the  first  portion  may  be  rendered  quite  secure 
before  the  adjacent  portions  are  dealt  with ;  and  the 
operation  necessarily  involves  excavating  underneath  a 


Levels  and  Gradients  of  Railway.  7 

short  length  of  foundation,  and  supporting  it  tem- 
porarily by  beams  and  props.  This,  and  the  avoidance 
of  settlement,  constitute  some  of  the  main  difficulties 
in  carrying  out  underground  work  through  towns.  A 
brick  arch  has  been  adopted  for  the  top  of  the  covered 
way,  wherever  the  depth  below  the  surface  was  suffi- 
cient, as  being  cheaper  and  more  durable  than  iron 
girders ;  but  in  places  where  the  headway  was  inade- 
quate, girders  have  been  employed.  The  covered  way 
supports  a  great  many  buildings  erected  since  the 
construction  of  the  line ;  and  extreme  instances  of  the 
weights  thus  imposed  are  noticeable  at  Westminster 
and  Blackfriars  stations,  where  buildings  80  feet  high 
are  borne  on  girders  spanning  these  stations.  It  is  to 
be  hoped  that  these  girders  may  be  successfully  pro- 
tected from  corrosion ;  for  such  a  massive  weight,  rest- 
ing on  a  girder,  imperceptibly  but  gradually  weakened 
by  the  oxidising  influences  to  which  it  is  exposed,  would 
be  liable  in  course  of  time  to  a  serious  catastrophe. 

The  importance  of  placing  the  numerous  stations 
within  easy  access  of  the  surface  has  led  to  the  line 
being  laid  out,  for  the  most  part,  in  conformity  with 
the  surface  slopes  of  the  ground,  just  as  in  an  ordinary 
railway,  with  ascending  and  descending  gradients,  but 
so  as  to  keep  always  at  a  suitable  depth  below  the 
surface.  Owing  to  the  greater  elevation  of  the  ground 
in  the  northern  district,  the  level  of  the  railway  varies 
considerably  at  different  parts,  reaching  about  80  feet 
above  mean  sea  level  at  Edgware  Road,  on  the  Inner 
Circle ;  rising  to  167  feet  at  the  Swiss  Cottage,  on  the 
St  John's  Wood  branch ;  and  falling,  near  Victoria 
Station,  to  9  feet  below  mean  sea  level.  The  steepest 
gradient,  of  I  in  70,  occurs  in  rising  from  beyond 


8  Works  connected  with  Inner  Circle. 

Gloucester  Road,  through  the  Campden  Hill  tunnel, 
to  Notting  Hill  Gate ;  and  the  next  steepest,  of  i  in  75, 
in  rising  from  the  valley  of  the  old  Westbourne  stream 
to  Paddington.  The  sharpest  curves,  of  10  chains  (220 
yards)  radius  on  the  Inner  Circle,  and  6f  chains  (147 
yards)  radius  on  the  King's  Cross  branch,  are  of  smaller 
radius  than  commonly  employed,  and  in  the  latter  case 
the  smallest  curve  that  has  been  adopted  on  a  line  of 
ordinary  gauge ;  but  these  curves  were  required  to  keep 
the  railway  within  certain  boundaries  of  property,  and  to 
form  connections  with  existing  lines,  and  the  trains  are 
never  run  at  high  speed  over  them.  In  consequence  of 
the  proximity  to  the  surface  at  which  the  railway  was 
formed,  the  excavations  were  mainly  carried  through  the 
alluvial  deposits  of  the  Thames  valley,  and  made  ground, 
overlying  the  London  clay  which  was  reached  towards 
the  bottom  of  some  of  the  excavations,  and  through 
which  the  Clerkenwell  tunnel  was  driven. 

One  of  the  most  interesting  portions  of  the  Inner 
Circle  is  where  the  Great  Northern  branch  from  King's 
Cross  dips  under  the  main  line,  in  order  to  branch  off 
on  the  opposite  side  to  Snow  Hill,  so  that  the  Under- 
ground Railway  is  actually  burrowed  under  by  another 
line ;  and  at  one  place  passengers  by  the  main  line 
can  see  the  crossing  train  almost  vertically  below  them 
through  the  open  girder  work  supporting  the  line  on 
which  they  are  travelling.  Advantage  was  taken  of 
the  Thames  Embankment  Works  to  construct  simul- 
taneously the  Underground  Railway  from  Westminster 
to  Blackfriars,  through  the  land  reclaimed  by  the 
Embankment;  and  a  much-needed  street  improvement 
was  effected,  in  conjunction  with  the  construction  of 
the  last  link  of  the  Inner  Circle  between  the  Monument 


Sewers  carried  across  Railway.  9 

and  the  Tower.  The  railway,  on  passing  from  under 
Cannon  Street  across  King  William  Street,  had  to  be 
carried  directly  under  the  granite  statue  of  William  IV., 
weighing  160  tons,  which  had  to  be  most  carefully 
underpinned  previous  to  the  carrying  out  of  the  excava- 
tions, and  now  rests  on  the  top  of  the  brick  arch  of 
the  covered  way,  so  that  the  trains  run  exactly  under- 
neath the  statue.  The  intersected  sewers  were  lowered 
for  some  distance  on  each  side  of  the  line,  where 
practicable,  and  carried  under  the  railway.  In  some 
instances,  however,  the  sewers  had  to  be  taken  over 
the  railway,  an  example  of  which  arrangement  may  be 
observed  at  Sloane  Square  Station,  where  the  Ranelagh 
sewer  is  carried  in  a  cast-iron  tube,  9  feet  in  diameter, 
across  the  upper  part  of  the  station,  being  supported 
by  girders  on  each  side.  The  Fleet  sewer  and  the 
Middle  Level  sewer  have  been  similarly  carried  over 
the  railway.  The  sewer  running  down  the  middle  of 
Cannon  Street,  Eastcheap,  and  Great  Tower  Street 
had  to  be  removed,  and  two  new  sewers  had  to  be 
constructed,  running  outside  the  covered  way  on  each 
side ;  and  the  increased  width  consequently  occupied 
by  the  works  necessitated  the  underpinning  of  most  of 
the  houses  along  these  streets.  The  provisions  requisite 
for  the  temporary  diversion  of  the  sewers,  and  other 
pipes,  during  the  progress  of  the  works,  naturally  added 
considerably  to  the  difficulties  experienced  in  pushing  for- 
ward the  operations  in  the  very  limited  space  available. 

When  the  Metropolitan  Railway  was  first  designed, 
it  was  intended  that  the  traffic  should  be  worked  by 
smokeless,  hot-water  locomotives,  not  burning  fuel,  as 
it  was  supposed  that  the  trains  would  be  small,  and 
that  locomotives  from  other  lines  would  not  travel  over 


io         Deficient  Ventilation  on  Inner  Circle. 

it  to  any  important  extent.      Accordingly,  no  attention 
was  paid  to  the  subject  of  ventilation  in  the  first  sec- 
tion of  the  Metropolitan  Railway ;  and  the  Baker  Street, 
Portland    Road,   and    Gower   Street   stations   were   built 
entirely   underground.      When,   however,   on   the    open- 
ing of  the  line,   heavy  locomotives  of  the  ordinary  type 
were    adopted,  the   glass  had  to  be  removed  from   the 
side  openings   at  these  stations,  and  openings  made  in 
portions    of  the    covered    way,    to    afford    an    outlet   for 
the   smoke  from   the  engines  ;   and  even  now  at  times 
the   relief    thereby   afforded    is    very   imperfect    at   the 
stations   above   mentioned.      These   defects    in   ventila- 
tion   have    been    avoided    in    the    more    recently   con- 
structed portions  of  the  line,  by  placing  the  stations  in 
uncovered    places    where    possible,   with    access   to   the 
open    air    at   each    end,    and   with   occasional    openings 
between    the    stations.      Where,   as    at    Cannon    Street 
and   Mark  Lane  stations,  access  to  the  open  air  above 
the     stations    was     impracticable,     large     openings    for 
ventilation   have  been  provided    at   the  side ;   and    fans 
for    producing    artificial    ventilation    have    been    set   up 
along   this    section   of    the   line.      In    spite   of  all    the 
precautions     taken     and     improvements     adopted,     the 
atmosphere  at  some  of  the  stations  is  still  considerably 
vitiated    on    damp,   oppressive    days    by    the    offensive 
smoke  from  the  locomotives ;  and  the  removal  of  this 
nuisance,    by    the     adoption    of    some    other    form    of 
motive    power    not     open    to    this    objection,    such    as 
electricity,  would  unquestionably  add   to  the  popularity 
of    the    Underground     Railway.       If    the    Inner    Circle 
formed  a  separate   system,   without  suburban   branches, 
and  without   connections  with   other  lines,  there   ought 
to  be  no   difficulty  in    introducing  a  smokeless   motive 


Smokeless  System  of  Traction  needed.          1 1 

power ;  but  the  matter  is  complicated  by  the  variety 
of  the  connections,  and  the  distances  to  which  some 
of  the  branches  extend.  Some  trains  merely  traverse 
a  portion  of  the  Inner  Circle  on  their  way  from  one 
place  to  another,  as  for  instance  from  Richmond  to 
New  Cross,  and  from  Woolwich  to  Finsbury  Park; 
whilst  trains  run  from  the  metropolitan  railways  to 
Edgeware,  Enfield,  Hatfield,  Hendon,  Brentford, 
Ealing,  Hounslow,  Wimbledon,  Willesden,  the  Crystal 
Palace,  and  Chesham.  Any  special  system  of  traction 
could  not  therefore  be  easily  applied  to  such  varied 
routes,  on  some  of  which  the  trains  are  drawn  by 
locomotives  belonging  to  different  companies.  Even, 
however,  if  a  smokeless  system  was  only  adopted 
for  the  Inner  Circle  trains,  and  those  passing  also 
over  the  loop  round  by  Addison  Road,  the  line  would 
be  relieved  from  the  smoke  of  over  eighteen  trains 
per  hour  throughout  the  day,  or  about  one  in  every 
three  minutes,  which  would  greatly  reduce  the  vitiation 
of  the  air  throughout  the  covered  portions  of  the  line. 

The  extensions  of  the  Metropolitan  Railway  have  far 
exceeded  the  anticipations  of  its  early  promoters,  who  con- 
templated merely  a  sort  of  improved  and  accelerated  un- 
derground omnibus,  or  tramcar  service ;  whereas  the  railway 
is  now  in  communication  with  most  of  the  metropolitan 
lines,  and  luggage  trains  may  be  seen  passing  over  it  late 
in  the  evening.  The  public  mind,  also,  is  occasionally 
somewhat  startled  by  hearing  of  the  proposed  extension 
of  the/  Underground  Railway'  to  Aylesbury,  and  even  to 
Oxford,  which  is  considered  an  unwarranted  departure 
from  its  mole-like  character.  The  Inner  Circle  alone, 
which  constitutes  the  real  underground  railway,  has 
a  length  of  only  I3TV  miles;  whereas  the  Metropolitan 


1 2         Railways  connected  with  Inner  Circle. 

Railway  has  nearly  20  miles  of  line  open,  and  the 
Metropolitan  District  Railway,  owned  by  a  separate 
company,  has  13  miles  open,  making  a  total,  with  the 
city  link  jointly  owned  by  the  two  companies,  of  34^ 
miles.  The  extensions  of  the  Metropolitan  to  Chesham, 
and  of  the  Metropolitan  District  to  Hounslow,  Rich- 
mond, and  Wimbledon,  have  indeed  made  these  lines 
cease  to  be  exclusively  metropolitan,  whilst  extending 
their  capabilities  and  advantages.  The  Inner  Circle,  how- 
ever, will  always  remain  the  special  feature  of  these  rail- 
ways, on  account  both  of  the  novelty  of  the  design,  and 
the  special  difficulties  involved  in  its  construction.  It 
has  also  satisfactorily  achieved  one  of  the  main  objects 
kept  in  view  by  the  legislature  during  its  development, 
namely,  the  connection  of  the  termini  of  the  various 
lines  entering  London  ;  for  it  is  in  direct  communication 
with  the  Great  Western,  the  Great  Northern,  the  Mid- 
land, and  the  Chatham  and  Dover  railways  near  their 
termini ;  with  the  East  London  Railway,  through  White- 
chapel,  and  thence  with  the  Great  Eastern,  Brighton,  and 
South-Eastern  railways.  The  Inner  Circle  is  also  in  fairly 
direct  communication  with  Cannon  Street  Station,  on 
the  South-Eastern,  through  Snow  Hill,  Holborn  Viaduct, 
and  Blackfriars  Bridge,  and  is  connected  somewhat  cir- 
cuitously  with  the  North- Western  and  North  London 
railways  through  Willesden  ;  with  Victoria,  by  Battersea  ; 
and  with  the  South-Western  by  a  similar  route.  More- 
over, Praed  Street  Station  adjoins  Paddington,  Gower 
Street  Station  is  near  Euston,  King's  Cross  Station  is 
close  to  both  St  Pancras  and  the  Great  Northern  ter- 
minus, and  Bishopgate  Station  adjoins  Broad  Street  and 
Liverpool  Street  stations  ;  whilst  Cannon  Street,  Charing 
Cross,  and  Victoria  stations,  on  the  Inner  Circle,  are 


Accommodation  afforded  by  Inner  Circle.       13 

very  near  to  the  respective  termini  of  the  same  names. 
Waterloo  Station  alone  is  at  a  little  distance  from  the 
Inner  Circle,  owing  to  its  situation  on  the  opposite  side 
of  the  Thames ;  but  even  in  this  case,  Westminster 
Bridge  and  Charing  Cross  stations  are  as  close  to  Water- 
loo as  circumstances  permit. 

Considering  the  scattered  positions  of  the  various 
termini  of  the  railways  entering  London,  and  the  diffi- 
culties inseparable  from  the  construction  of  a  railway 
right  across  London,  it  must  be  acknowledged  that  the 
Inner  Circle,  though  the  result  of  several  successive  ex- 
tensions, has  been  remarkably  well  laid  out,  as  a  whole, 
for  accommodating  the  various  lines  ;  while,  at  the  same 
time,  it  gives  quick  and  easy  communication  between 
distant  parts  of  the  metropolis,  and  even  between  one 
suburb  and  another  on  opposite  sides  of  London.  The 
Great  Western,  Midland,  and  Great  Northern  railways 
have  specially  profited  by  the  Underground  Railway, 
for  they  are  indebted  to  it  for  their  access  to  the  city, 
and  the  consequent  development  of  the  suburban  traffic 
along  their  lines.  Moreover,  though  the  final  link  in 
the  city,  which  completed  the  circuit  of  the  Inner  Circle, 
has  not  hitherto  brought  the  traffic  anticipated  from 
the  trains  being  able  to  run  round  continuously  in  both 
directions,  owing  probably  to  the  considerable  elonga- 
tion of  the  narrow  end  of  the  oval  eastwards,  this  link, 
with  the  Whitechapel  extension,  has  placed  the  populous 
East  End  and  the  eastern  suburbs  in  direct  communica- 
tion with  the  Inner  Circle  and  its  numerous  branches. 

The  rapid  succession  of  trains  on  the  Inner  Circle 
required  for  serving  the  Addison  Road  loop,  and  the 
numerous  branches,  in  addition  to  the  Circle  trains 
running  at  intervals  of  ten  minutes  each  way  through- 


14  Block  System  for  Safety  of  Traffic. 

out   the   day,   has   been   only  rendered    possible   of  ac- 
complishment by  the  introduction  of  the  block  system 
and  the  employment  of  continuous  brakes.     The  block 
system    insures,    by    a    carefully    arranged    system     of 
signalling,  that,  if  the  engine-driver  pays   proper  atten- 
tion   to   the   signals   exhibited,    no   two    trains    on    the 
same    line    shall    be    in    the    same    block,    or    interval 
between  two  adjacent  signal  cabins,  at  the  same  time. 
Each  signalman   is  instructed   not    to    lower  his  signal, 
and    by   the    most   recent   electrical    contrivance    he    is 
prevented  from  lowering  his  signal,  for   the   passage   of 
a  train,  till  the  signalman  in  the  next  cabin  in  advance 
informs  him,  by  telegraph,  of  the  passage  of  the   train 
in    front   past   that    cabin,    and    consequently   that    the 
interval   between  the  two  cabins  is  empty.     The  occur- 
rence of  accidents  is  accordingly  prevented,  if  the  signals 
are  obeyed,  by  interposing  an  interval  of  space  between 
each  train  and  the  next.      There   are   signal    boxes    at 
every  station ;    and   intermediate  cabins   are   sometimes 
placed  between  the  stations  where  the  interval  is  rather 
greater,  or  the  traffic  very  large,  notwithstanding  the  small 
distance   between    the   stations    along  the   Inner  Circle. 
The  number  of  blocks,  indeed,  into  which  a  railway  can 
be  divided  is  only  limited   by  the  necessity  of  making 
the  shortest  block   longer   than   the    longest   train ;   but 
whilst    a    greater   number    of    blocks   within    a    certain 
distance  increases   the  number   of  trains  which   can    be 
admitted  to  that  section  of  a  railway  at  the  same  time, 
it  reduces  the  speed  of  the  trains,  owing  to  the  frequency 
of  the  signal  boxes  at  which  the  engine-driver  must  be 
prepared  to  pull  up  if  necessary.     The  accommodation, 
however,  of  a  number  of  trains  is  of  more  importance  on 
the   metropolitan    railways  than   great    speed ;   and    the 


Value  of  Continuous  Brakes.  1 5 

continuous  brake  enables  the  train  to  be  pulled  up  within 
a  very  short  distance,  on  approaching  a  signal  set  at 
danger.  The  continuous  brake  puts  a  brake  on  the 
wheels  of  every  carriage  of  a  train  simultaneously, 
instead  of  the  brake  being  only  applied  to  the  engine 
and  the  guard's  van,  as  in  former  days ;  and  thus,  by 
increasing  the  frictional  area  and  applied  weight,  a  train 
entering  a  station  at  a  good  speed  can  be  brought  to  rest 
by  the  time  the  engine  has  reached  the  further  end  of 
the  station.  This  rapid  stoppage  of  the  train,  combined 
with  the  quick  starting  again  of  the  engines,  reduces 
the  time  occupied  at  stations  to  a  minimum ;  so  that 
the  average  period  of  transit  between  the  stations, 
including  stoppages,  on  the  Inner  Circle  is  only  about 
2 1  minutes.  Accordingly,  the  continuous  brake,  besides 
ensuring  a  greater  immunity  from  accidents,  facilitates 
rapidity  of  transit.  Iron  rails  wore  rapidly  under  the 
much  increased  friction,  due  to  the  augmented  brake 
power,  entailing  frequent  repairs  and  costly  renewals. 
The  introduction,  however,  of  heavy  steel  rails,  at  a 
moderate  cost,  has  greatly  increased  the  durability 
of  the  rails,  and  reduced  the  expenses  of  maintenance. 
The  success,  therefore,  and  safe  working  of  the  numerous 
trains  running  on  the  Inner  Circle  are  due  to  a  com- 
bination of  a  variety  of  improvements ;  and  the  only 
important  amelioration  which  appears  needful  is  an 
improved  ventilation  of  the  covered  way. 

Metropolitan  Railway  proposed  for  Paris. — The  great 
advantages  derived  from  the  London  metropolitan  rail- 
ways have  led  to  various  schemes  for  obtaining  similar 
accommodation  in  the  centre  of  Paris.  The  outskirts 
of  Paris  are  served,  and  the  several  lines  converging  on 


1 6     Paris  and  Berlin  Metropolitan  Railways. 

Paris  are  connected,  by  the  '  chemin  de  fer  de  ceinture,' 
or  Outer  Circle,  which  completely  encircles  Paris  on  the 
outside.  The  growing  density,  however,  of  the  popula- 
tion in  Paris  renders  additional  and  more  rapid  means 
of  communication  within  the  city  very  desirable.  Schemes 
for  overhead  railways,  on  masonry  viaducts,  connecting 
the  most  important  parts  of  the  town,  have  been  proposed, 
as  well  as  underground  lines  resembling  in  principle  the 
Inner  Circle.  No  scheme  has,  hitherto,  been  finally 
adopted,  though  the  circular  underground  or  partly 
underground  lines  seem  to  be  preferred,  the  hesitation 
about  providing  the  necessary  capital  being  apparently 
partly  due  to  the  poor  returns  on  part  of  the  capital 
invested  in  the  London  Underground  Railway. 

Berlin  Metropolitan  Railway. — Berlin,  like  Paris, 
possesses  an  outer  circle  railway  connecting  the  various 
Berlin  railways,  and  serving  the  suburbs.  It  was  con- 
sidered impracticable  to  make  a  circular  underground 
line  in  Berlin,  owing  to  the  level  of  the  River  Spree, 
which  runs  through  the  city.  A  metropolitan  railway 
has,  consequently,  been  constructed  on  a  viaduct, 
forming  a  diameter  to  the  Outer  Circle  Railway.  It 
connects  the  Charlottenburg  Station,  at  the  west  end, 
with  the  Silesia  Station,  at  the  east  end,  having  a  total 
length  of  7J  miles,  with  four  lines  of  way  to  keep  the 
through  and  local  traffic  distinct.  This  line  has  nine 
stations;  it  was  commenced  in  1875,  and  completed  in 
1882. 

THE   NEW  YORK   ELEVATED   RAILWAYS. 

Manhattan  Island,  on  which  the  city  of  New  York 
is  situated,  has  an  average  width  of  2  miles,  with  a 


Objects  of  New  York  Elevated  Railways.       17 

length  of  13  miles.  The  business  part  of  the  city  is 
concentrated  at  the  southern  end  of  the  island  ;  and, 
owing  to  the  narrowness  of  the  island  in  proportion  to 
its  length,  easy  and  rapid  means  of  communication  was 
required  from  the  southern  end  northwards,  that  a 
development  of  the  city  to  the  north,  for  residences, 
might  accommodate  the  increasing  population,  which,  for 
want  of  convenient  access,  tended  to  crowd  up  towards 
the  southern  part.  In  1867,  the  engineers  of  New  York 
set  to  work  at  the  development  of  the  needed  railway 
facilities  across  the  city  in  a  characteristic  manner. 
Burrowing  underground  involves  costly  works  and  un- 
foreseen contingencies,  especially  on  an  island  where 
the  neighbourhood  of  two  deep  rivers  rendered  pro- 
bable the  presence  of  alluvial  deposits  in  places, 
and  consequently  treacherous  foundations.  An  or- 
dinary railway,  on  an  arched  viaduct,  necessitates  a 
heavy  expenditure  in  the  purchase  of  valuable  land,  as 
well  as  the  cost  of  the  works  themselves,  including 
spanning  by  bridges  the  streets  traversed.  The  method 
of  construction  commenced  in  1867,  and  subsequently 
extended,  has  enabled  the  New  York  Elevated  Railway 
Companies  to  avoid  underground  operations,  and  at  the 
same  time  to  escape  from  any  purchase  of  land.  The 
railways  have  been  carried  along  the  streets ;  they  are 
raised  above  the  street  traffic  on  girders  resting  upon 
wrought-iron  lattice  columns,  standing  at  convenient 
places  on  the  line  of  the  curb  of  the  pavements,  or  in 
the  roadway  itself  where  the  traffic  is  not  too  heavy 
or  the  streets  too  narrow.  (See  illustration.)  No  pay- 
ment has  been  made  for  placing  these  columns  along 
the  streets ;  and  no  compensation  has  been  paid  for 
damages  to  residential  property  fronting  the  avenues 

B 


1 8  Construction  of  Elevated  Railway. 

and  streets  which  the  railways  traverse,  though  the 
trains  are  constantly  running  a  very  short  distance  off, 
and  on  the  level  of  the  first-floor  windows.  The  deprecia- 
tion, due  to  the  continual  noise  and  loss  of  privacy,  has 
reached  in  some  cases  as  much  as  fifty  per  cent. 

The  columns,  which  support  the  girders  over  which 
the  trains  run,  are  placed  at  intervals  of  from  37  to 
44  feet  along  the  curb,  on  each  side  of  the  road- 
way, where  the  street  is  too  narrow  or  too  crowded 
with  traffic  to  allow  of  the  columns  being  placed 
in  the  roadway.  In  these  cases,  if  the  proximity 
of  the  railway  to  the  houses  is  of  no  consequence,  the 
columns  are  widened  out  at  the  top  to  carry  the  two 
longitudinal  girders,  placed  5  feet  apart,  directly  under 
each  rail ;  and,  under  these  circumstances,  the  up  and 
down  trains  run  exactly  over  the  line  of  columns  placed 
along  the  curb  on  each  side  of  the  roadway.  If,  on  the 
contrary,  it  is  important  to  keep  the  railway  as  far  as 
possible  from  the  houses  on  each  side,  girders  are 
fastened  on  each  pair  of  columns  across  the  street,  from 
28  to  45  feet  long,  according  to  the  width  of  the  street ; 
and  these  girders  carry  the  longitudinal  girders  placed 
under  the  rails,  which  can  thus  be  brought  nearer  to 
the  centre  of  the  street  than  the  lines  of  columns,  the 
centres  of  the  up  and  down  lines  being  not  more  than 
20  feet  apart.  Where  the  roadway  is  wide,  and  not  so 
frequented  as  to  render  the  erection  of  columns  in  it 
inadmissible,  the  rows  of  columns  are  placed  along  the 
roadway,  at  a  clear  distance  apart  of  22  feet,  so  that 
two  tramway  lines  can  pass  between  them.  The  columns 
are  widened  out  at  the  top,  as  in  the  first  example  de- 
scribed, so  as  to  receive  the  longitudinal  girders  placed 
under  each  rail ;  and  the  whole  structure  is  further 


Gradients  and  Curves  of  Railway.  1 9 

strengthened  by  bracing  together  the  pairs  of  columns 
across  the  street,  at  the  level  of  the  girders.  A  minimum 
clear  height  of  14^  feet  is  provided  under  the  girders, 
so  that  the  traffic  along  the  roadways  may  not  be  in- 
terfered with.  The  gradients  of  the  railway  follow 
approximately  the  inclination  of  the  roadway,  except 
where  frequent  changes  of  inclination,  or  a  steep  inclin- 
ation, render  a  modification  of  the  gradient  for  the  rail- 
way expedient.  The  columns,  accordingly,  vary  in 
height  according  to  circumstances,  the  variation  gener- 
ally being  between  1 8  and  2 1  feet ;  but  in  one  part 
columns  65  feet  high  have  been  adopted,  which  have 
been  specially  braced  together  in  groups  to  ensure 
stability.  The  steepest  gradient  of  these  railways  is  I  in 
50.  Owing  to  the  avenues  and  streets  in  New  York  being 
at  right  angles,  and  the  necessity  for  the  railway  to  keep 
to  the  line  of  the  roadway,  the  curves  on  the  railway  for 
changing  its  course  are  necessarily  very  sharp ;  and 
the  sharpest  curve  on  the  main  line  has  a  radius  of  a 
little  under  \\  chains  (33  yards),  though  the  gauge  of  the 
railway  is  the  same  as  the  ordinary  gauge  of  Great  Britain. 
Such  a  small  curve  is  more  in  conformity  with  the 
practice  of  tramway  lines  on  roads ;  and,  compared  with 
this,  the  minimum  curve  on  the  London  Metropolitan  Rail- 
way, of  6f  chains  (147  yards),  appears  ample;  but,  on  the 
New  York  Elevated  Railway,  special  bogie  locomotives 
are  exclusively  employed,1  whilst  any  locomotive  may 
have  to  pass  over  the  Metropolitan. 

The    first    portion    of   the    Elevated    Railway,    con- 
structed in    1867,  was   worked    by  a  wire   rope,   moved 

1  The  term  bogie  is  applied  to  the  two  pairs  of  small  wheels  and  frame- 
work pivoted  centrally  under  the  frame  of  the  front  of  a  locomotive,  or 
towards  each  end  of  a  long  car,  which,  by  turning  independently,  enables 
the  locomotive  and  car  to  pass  easily  round  sharp  curves. 


2O  Features  of  Elevated  Railway. 

by  a  stationary  engine;  and  owing  to  the  want  of  suc- 
cess of  this  system,  no  further  progress  was  made 
till  1875,  when  a  commission  reported  in  favour  of  the 
elevated  system  of  railways  in  preference  to  the  under- 
ground plan,  which  resulted  in  the  construction  of  the 
xisting  lines  of  railways  in  New  York.  The  Elevated 
Railway  has  been  carried  along  the  Second,  Third,  Sixth, 
and  Ninth  Avenues  ;  and  it  also  has  branches,  one  of 
which  connects  it  with  the  New  York  Central  Railway, 
and  another  with  the  New  York  City  and  Northern 
Railway.  The  elevated  railways  are  owned  by  two 
separate  companies,  and  worked  by  a  third  company, 
to^whom  the  lines  are  leased  for  199  years,  by  means 
of  locomotives,  with  coupled  driving  wheels  3-}  feet 
in  diameter,  and  bogie  wheels  2  feet  in  diameter.  The 
total  length  of  the  lines  is  about  32^-  miles. 

The  stations  on  the  Elevated  Railway  are  about  one- 
third  of  a  mile  apart,  which  is  somewhat  closer  than 
on  the  London  Inner  Circle,  where  the  average  distance 
between  the  stations  is  half-a-mile.  The  trains  are 
necessarily  provided  with  continuous  brakes,  to  allow 
the  frequent  stoppages  to  be  rapidly  effected.  In  the 
busiest  part  of  the  day,  the  trains  run  at  intervals  of 
two  minutes,  and  at  other  times  at  intervals  of  four  or 
five  minutes.  There  are  no  parapets  or  railings  along 
the  line,  and  the  width  of  the  cars  is  equal  to  the 
length  of  the  cross  sleepers.  Gates  are  placed,  therefore, 
across  the  platforms  at  the  ends  of  the  cars,  which  are 
only  opened  at  the  stations  ;  for  any  passenger  leaving 
the  train,  except  alongside  the  station  platform,  would  be 
precipitated  into  the  street.  Guard  timbers  are  laid 
on  both  sides  of  each  rail  to  secure  the  trains  from 
leaving  the  road,  for  such  an  accident  would  not 


Cost  and  Peculiarity  of  Design.  2 1 

merely  involve  injury  to  the  passengers,  but  serious 
casualties  to  the  persons  in  the  street  below.  Open 
spaces  of  one  foot  in  width  are  left  between  the  cross 
sleepers  along  the  line,  so  that  anything  dropping  from 
the  engine,  except  at  the  stations,  where  protection  is 
afforded,  is  liable  to  fall  on  the  people  underneath.  This, 
together  with  the  frequent  noise  of  the  passing  trains, 
must  be  a  nuisance  to  the  people  traversing  the  streets. 

The  cost  per  mile  of  the  Elevated  Railway  was 
only  ;£8i,OOO,  which  appears  a  very  small  amount 
when  compared  with  the  cost  per  mile  of  the  London 
metropolitan  railways,  amounting  to  about  ^575,000, 
which  indicates  the  great  financial  advantages  of  the 
permission  to  construct  overhead  railways  along  the  main 
thoroughfares,  and  of  being  exempted  from  the  purchase 
of  land,  and  from  the  payment  of  compensation. 

The  Elevated  Railway  is  a  marvel  to  the  English 
visitor  in  New  York,  not  on  account  of  any  special 
skill  exhibited  in  the  design,  which  is  quite  simple,  but 
owing  to  the  contrast  it  presents  to  the  system  of 
railways  in  London,  the  boldness  of  the  conception  of 
carrying  an  overhead  railway  along  crowded  thorough- 
fares, and  the  impossibility  of  obtaining  powers  for  any 
similar  construction  in  England.  A  comparison  of  the 
Metropolitan  Railway  with  the  Elevated  Railway  forcibly 
manifests  the  different  views  entertained  in  the  two 
countries,  with  regard  to  the  rights  of  railway  com- 
panies in  relation  to  the  streets,  and  as  to  the  claims 
of  owners  of  house  property  for  compensation  for 
injuries  inflicted.  The  boldest  part  of  the  design  con- 
sists in  placing  a  railway  on  the  top  of  a  narrow  super- 
structure, resting  upon  a  single  row  of  isolated  columns, 
only  ij  feet  by  ij  feet  wide,  placed  44  feet  apart, 


2  2  Success  of  Elevated  Railway. 

along  the  curb  on  each  side  of  a  crowded  roadway, 
and  then  allowing  trains  to  run  constantly,  at  a  speed 
of  1 8  miles  an  hour,  along  this  open,  unpro- 
tected track,  which  has  a  maximum  width  of  8  feet 
at  the  top.  The  work  has  proved  an  engineering 
success  ;  it  has  attracted  a  very  large  and  increasing 
traffic,  and  has  effected  the  desired  development  of 
the  northern  part  of  the  island  of  Manhattan ;  whereas 
previously  the  want  of  means  of  access  forced  the 
increasing  population  to  migrate  in  large  numbers  to 
Jersey  City  and  Brooklyn.  Imperative  necessity,  how- 
ever, could  alone  justify  such  a  method  of  construction, 
which,  though  doubtless  very  convenient  to  the  pass- 
engers, must  be  a  source  of  discomfort  to  the  people 
passing  along  the  streets  below,  and  still  more  to 
those  living  alongside,  and  a  very  serious  loss  to  the 
householders  in  the  streets  traversed  by  the  railway.  The 
number  of  passengers  conveyed  by  the  railway  increased 
from  61  millions  in  1880  to  171^  millions  in  1888. 

The  London  metropolitan  and  New  York  elevated 
railways  have  been  selected  for  description,  as  illus- 
trating two  novel  systems  of  railway  construction  in 
the  latter  half  of  the  nineteenth  century,  under  cir- 
cumstances of  peculiar  difficulty  ;  but  they  constitute 
only  a  very  small  part  of  the  general  development 
of  railway  construction  and  traffic  which  has  occurred 
during  this  period.  It  is  sufficient  to  turn  to  the  Re- 
turns, issued  yearly  by  the  Board  of  Trade,  to  see  how 
great  the  railway  development  has  been,  since  the 
middle  of  the  century,  in  the  United  Kingdom  alone. 
In  1849,  the  number  of  miles  of  railway  open  in  the 
United  Kingdom  was  6031  ;  it  is  now  19,943,  so  that  the 


Capital  and  Traffic  of  British  Railways.      2  3 

total  length  of  railways  has  been  trebled  within  the  last 
forty  years.  The  capital  invested  was  £230,000,000 
in  round  numbers  in  1849,  and  £876,600,000  in  1889, 
showing  that  the  capital  invested  in  railways  in  the 
United  Kingdom  has  been  nearly  quadrupled  in  the 
last  forty  years.  The  number  of  passengers  carried, 
exclusive  of  season  ticket  holders,  was  64,000,000  in 
1849,  and  775,000,000  in  1889,  indicating  that  the 
railway  passengers  now  are  more  than  twelve  times 
the  number  forty  years  ago,  without  allowing  for  the 
great  increase  in  the  season  ticket  holders.  These  figures 
show  that  the  capital  has  increased  in  a  greater  ratio  than 
the  length  of  lines  opened,  owing  doubtless,  in  great 
measure,  to  the  doubling  of  the  lines  near  London, 
which  is  not  taken  account  of  in  the  Returns,  improved 
station  accommodation,  and  costly  extensions.  The 
passengers,  however,  have  increased  in  a  far  greater 
proportion  than  the  capital,  showing  the  advantages  of 
improved  accommodation,  and  the  growing  propensity  of 
the  population  to  travel.  The  growth  of  the  passenger 
traffic  is,  indeed,  very  steady,  for  there  has  been  an  in- 
crease every  year  in  the  numbers  for  the  last  forty  years, 
with  the  sole  exception  of  1879,  when  there  was  a 
slight  decrease  as  compared  with  1878,  which  was, 
however,  much  more  than  recovered  in  the  following 
year.  These  figures,  relating  to  the  United  Kingdom 
alone,  give  some  faint  idea  of  the  marvellous  develop- 
ment of  railways  since  the  middle  of  the  century,  not 
merely  throughout  Europe,  but  in  almost  every  civil- 
ised country,  with  the  exception  of  China  This 
enormous  extension  of  railways,  and  the  greatly 
increased  facilities  thereby  afforded  for  travelling  to 
the  constantly  growing  population  of  the  world,  are 


24  Safety  of  Railway  Travelling. 

the  combined  results  of  the  skill  of  the  engineer,  the 
energy  of  the  contractor,  the  labour  of  his  men,  and 
the  confidence  of  the  capitalists  in  the  success  of  the 
undertakings.  A  very  satisfactory  feature  in  the  great 
increase  of  traffic  is  that  the  improvements  in  safety 
appliances  have  more  than  kept  pace  with  the  growth 
of  traffic,  so  that  railway  travelling,  in  spite  of  the 
much  greater  frequency  of  trains,  is  safer  than 
formerly ;  and  it  is  certain  that  a  person  is  more 
secure  from  accident  in  a  railway  carriage  than  when 
walking  through  the  crowded  parts  of  London. 


CHAPTER    II. 

RAILWAYS   ACROSS   THE  ALPS,   THE   ROCKY  MOUNTAINS, 
AND   THE   ANDES. 

THE  gradients  and  curves  adopted  for  a  railway, 
through  a  hilly  district,  exercise  a  very  important  in- 
fluence on  the  cost  of  construction  ;  for  with  steep 
gradients  and  sharp  curves,  it  may  be  possible  to 
follow  approximately  the  general  levels  of  the  ground, 
and  the  contours  of  the  valleys  ;  whereas  flat  gradients 
and  easy  curves  would  necessitate  deep  cuttings  and 
high  embankments,  in  order  to  pierce  the  ridges  and 
cross  the  valleys.  In  the  early  days  of  railway  enter- 
prise, when  the  main  lines  of  this  and  other  countries 
were  laid  out  along  the  most  suitable  routes,  it  was 
considered  expedient,  and  generally  found  practicable, 
to  adopt  in  most  places  gradients  rising  not  more  than 
i  foot  in  300  or  400  feet  of  length,  and  curves  having 
radii  of  little  less  than  one  mile.  This  course  has 
enabled  heavy  trains  to  run  with  safety  at  the  high 
speeds  now  so  common  on  many  main  lines.  On  the 
contrary,  steep  gradients  and  sharp  curves,  whilst  re- 
ducing the  first  cost  of  construction  in  rough  country, 
diminish  also  the  available  speed  and  tractive  power 
of  the  locomotives,  and  increase  the  wear  and  tear  on 
the  lines.  Accordingly,  economy  in  construction,  under 


26  Laying  out  Mountain  Railways. 

such  conditions,  involves  increased  cost  in  working  and 
maintenance ;  and  therefore  it  was  wise  in  the  earlier 
principal  main  lines,  with  a  large  traffic,  to  secure  rapid, 
easy  travelling  with  comparatively  moderate  working 
expenses,  at  the  cost  of  a  larger  capital  outlay  in  the 
heavier  portions  of  the  lines.  When,  however,  the 
development  of  railways,  and  the  public  demands  for 
increased  facilities  of  communication,  necessitated  the 
extension  of  railways  across  mountainous  districts,  the 
conditions  became  altered  ;  and  the  steep  gradients  and 
sharp  curves,  which  would  have  been  considered  quite 
inadmissible  in  early  days,  became  absolutely  essential 
for  carrying  railways,  at  any  reasonable  expense,  across 
the  Alps  and  the  Rocky  Mountains.  Moreover,  rail- 
way extensions  into  undeveloped  districts,  like  the 
western  parts  of  North  America,  are  the  pioneers  of 
civilisation,  and  require  to  be  carried  out  as  rapidly 
and  cheaply  as  possible,  leaving  improvements  in  the 
lines  to  be  effected  when  the  development  of  the 
countries  traversed  affords  sufficient  increase  of  traffic 
to  warrant  the  outlay. 


ALPINE  RAILWAYS. 

Semmering  Railway. — The  first  railway  carried 
across  the  Alps  was  constructed  by  the  Austrian 
Government,  in  1848-54,  to  connect  Vienna  with  its 
seaport  Trieste.  It  crosses  the  Styrian  Alps  at  the 
Semmering  Pass,  from  which  it  takes  its  name  of  the 
Semmering  Railway.  The  lowest  point  of  the  ridge, 
at  the  pass,  is  3248  feet  above  sea  level ;  but  the  rail- 
way pierces  the  top  of  the  ridge  by  a  tunnel  of 
nearly  a  mile  in  length,  so  that  its  summit  level  is 


Works  of  the  Semmering  Railway.  27 

only  2892  feet  above  sea  level.  Before  reaching  the 
tunnel,  however,  at  the  summit,  the  railway  has  to  rise 
1297  feet  in  a  little  less  than  13  miles,  going  through 
fourteen  tunnels  and  over  sixteen  viaducts  in  its  course, 
and  having  gradients  of  I  in  45  to  i  in  40  along  the 
greater  part  of  this  distance.  On  the  opposite  side  of 
the  ridge,  descending  towards  Trieste,  the  slope  is  less 
rugged ;  so  that  the  descent  to  Murzzuschlag,  of 
402  feet  in  7  miles,  has  been  effected  without  tunnels 
or  viaducts,  and  with  gradients  rarely  steeper  than 
i  in  45.  Accordingly,  this  railway,  which  cost 
^"98,000  per  mile,  or  more  per  mile  than  the  New 
York  Elevated  Railway,  was  not  able  to  be  con- 
structed, even  at  this  outlay,  without  gradients  which 
in  old  days  would  have  been  considered  excessive, 
amounting  to  from  eight  to  ten  times  the  steepness  at 
first  deemed  advisable  on  main  lines.  Moreover,  in 
addition  to  the  steep  gradients  and  heavy  works  on  the 
Vienna  side  of  the  ridge,  the  railway  had  to  be  carried 
up  this  slope  in  a  circuitous  line,  with  sharp  curves  of  as 
little  as  g\  chains  (209  yards)  radius,  so  as  to  wind  round 
the  projecting  spurs,  and  also  to  gain  an  easier  gradient 
by  an  increase  in  length.  This  is  the  only  instance  of 
quite  such  sharp  curves  being  adopted,  even  upon 
Alpine  railways ;  and  they  occupy  altogether  4^  miles 
of  the  line.  Such  a  combination  of  steep  gradients 
and  sharp  curves  on  a  main  line  was  unprecedented  in 
1854,  when  the  line  was  opened  for  traffic;  and  special 
locomotives  had  to  be  designed  for  traversing  this 
section  of  the  line.  The  passenger  locomotives  proved 
capable  of  drawing  passenger  trains  up  the  inclines,  at 
a  speed  of  i  if  miles  an  hour ;  and  eventually  two 
goods  locomotives,  one  in  front  and  one  behind,  were 


28          Traction  on  the  Semmering  Railway. 

able  to  take  up  goods  trains,  of  350  tons,  at  a  rate  of 
9^  miles  an  hour.  The  cost  of  traction  on  the 
Semmering  inclines  is  about  two  and  a  half  times  the 
cost  on  the  other  portions  of  the  line,  so  that,  in  this 
respect,  the  inclines  are  equivalent  to  an  addition  of 
one  and  a  half  times  the  length  of  this  section.  The 
speed,  under  the  most  favourable  conditions,  could  never 
be  much  increased  with  safety  over  such  sharp  curves 
on  a  line  of  ordinary  gauge.  The  Semmering  Railway 
was  the  precursor  of  other  Alpine  railways,  of  greater 
length  and  higher  elevation,  across  the  main  chains  of 
the  Alps ;  but  though  the  gradients  have  in  some 
cases  been  made  even  somewhat  steeper  than  on  the 
Semmering,  the  very  small  radius  of  the  sharpest 
curves  has  not  been  equalled  on  any  other  Alpine 
line,  or  even  approached,  except  in  one  instance.  Not- 
withstanding the  moderate  elevation  of  the  summit  of 
the  line,  trains  on  the  Semmering  are  occasionally 
impeded  by  snow. 

Brenner  Railway. — To  the  Austrian  Government 
belongs  the  honour  of  constructing  the  second  railway 
across  the  Alps,  as  well  as  the  first,  and  in  this  second 
case  across  the  main  Alpine  chain,  over  the  Brenner 
Pass.  The  object  of  the  Brenner  Railway  was  to 
connect  Austria  by  railway  with  its  possessions  in  the 
Tyrol  and  Venetia ;  but  as  a  result  of  the  war  with  Italy, 
in  1866,  the  latter  possessions  were  ceded  by  Austria 
to  Italy  before  the  completion  of  the  railway.  Though 
the  Brenner  Railway  was  a  much  greater  and  more 
formidable  undertaking  than  the  Semmering,  the  route 
is  the  most  favourable  one  for  crossing  the  main  chain 
of  the  Alps,  as  the  Brenner  is  the  lowest  of  the  main 


•TTTjrl 

^-4--4~yLt° 

I    S    5-    ?    1 


Works  of  the  Brenner  Railway.  3 1 

Alpine  passes,  and  is  less  encumbered  by  snow,  owing 
to  its  distance  from  the  highest  peaks.  The  total 
length  of  the  mountain  line  between  Innsbruck  and 
Botzen  is  78^  miles ;  and  the  summit  of  the  ridge  is 
crossed  without  any  tunnel,  at  a  height  of  4497  feet 
above  sea  level.  (See  page  30.)  The  rise  on  the 
northern  slope,  in  the  23  miles  between  Innsbruck  and 
the  summit,  is  2586  feet,  making  an  average  ascent  of 
I  in  47,  which  is  mainly  accomplished  by  gradients 
of  i  in  40  along  17^  miles  of  the  way.  The  fall  on 
the  southern  slope  is  3624  feet  in  the  55  \  miles  be- 
tween the  summit  and  Botzen,  giving  an  average 
descent  of  i  in  8 1,  in  which  the  steepest  gradient  is 
I  in  44,  which  extends  along  10^  miles  of  the  upper 
part  of  the  slope.  The  railway  passes  through  fourteen 
tunnels  on  the  northern  slope,  and  through  only  three 
tunnels  on  the  southern  slope,  which  is  less  steep  and 
rugged  than  the  other.  The  line  winds  along  the 
valleys  in  ascending  the  slopes ;  and  it  forms  a  long 
narrow  loop  about  half  way  between  Sterzing,  on  the 
southern  slope,  and  the  summit,  and  a  shorter  loop  on  the 
northern  slope.  This  winding  course  has  necessitated 
making  the  line  curved  for  nearly  half  its  length,  and 
the  introduction  of  curves  of  the  minimum  radius  of 
about  14  chains  (308  yards),  over  a  total  distance  of  9f 
miles.  The  express  trains  ascend  the  slopes  at  a  speed  of 
15^  miles  an  hour,  and  descend  at  23!  miles  an  hour. 

The  Brenner  Pass  possesses  the  interest  of  having 
been  the  first  main  Alpine  pass  traversed  by  carriages, 
and  also  the  route  by  which  Attila's  forces  and  other 
barbarian  armies  descended  on  Italy.  The  Brenner  Rail- 
way was  the  first  which  surmounted  one  of  the  principal 
chains  of  the  Alps,  and  the  only  one  which  has  done 


32  Works  of  the  Mont  Cents  Railway. 

so  without  a  summit  tunnel;  but  it  rises  to  a  greater 
elevation  than  any  of  the  others,  its  summit  level  being 
104  feet  higher  than  the  highest  level  of  the  Mont 
Cenis  Railway.  The  railway  passes  on  from  Botzen  to 
Verona,  and  thus  first  afforded  Austria  and  Germany 
direct  communication  with  Northern  Italy  and  the  port 
of  Briridisi.  It  was  commenced  in  1864,  and  completed 
in  1867. 

Mont  Cenis  Railway. — Though  the  Semmering  and 
Brenner  railways,  with  their  tortuous  course,  sharp 
curves,  and  exceptionally  long  and  steep  gradients, 
were  remarkable  examples  of  engineering  skill  and 
progress  in  surmounting  most  formidable  obstacles, 
they  did  not  attract  the  world-wide  notice  which 
another  mountain  line,  commenced  seven  years  before 
the  Brenner,  and  only  completed  about  four  years 
after  it,  has  done.  This  railway,  known  as  the  Mont 
Cenis,  from  the  pass  of  that  name  on  the  road  between 
France  and  Italy,  owes  its  renown  to  the  tunnel  of 
unparalleled  length  required  for  piercing  an  insurmount- 
able ridge  at  its  summit  level,  of  which  a  description 
will  be  given  in  a  following  chapter.  The  other 
features  of  the  line  are  very  similar  to  the  Semmering 
and  the  Brenner.  There  is,  however,  only  one  loop 
of  importance,  situated  near  the  French  end  of  the 
long  tunnel  ;  and  the  sharpest  curve  has  p.  radius  of  17 
chains  (374  yards).  On  the  other  hand,  the  gradients  are 
steeper  generally  than  those  on  either  of  the  earlier  lines, 
the  maximum  gradient  on  both  slopes  being  I  in  33^. 
The  rise  on  the  French  slope  is  2037  feet  in  the 
21  miles  from  St  Jean  de  Maurienne  to  the  entrance 
of  the  tunnel,  and  2683  feet  in  the  24^  miles  on  the 


Advantages  of  Mont  Cenis  Railway.          33 

Italian  slope,  between  Bussoleno  and  the  tunnel.  The 
line  passes  through  fourteen  tunnels  on  the  northern 
slope,  and  through  twenty-six  tunnels  and  over  eight 
viaducts  on  the  southern  slope.  The  open  portion  of 
the  railway  reaches  an  altitude  of  3793  feet  above 
sea  level  on  the  French  side,  and  4270  feet  on  the 
Italian  warmer  southern  side ;  but  these  elevations, 
though  inferior  to  the  summit  level  of  the  Brenner, 
are  exposed  to  the  chilling  influence  of  the  proximity 
of  the  highest  peaks  of  the  Alps.  The  Mont  Cenis 
Railway  gives  direct  communication  between  Paris 
and  Turin  ;  it  was  commenced  in  1857,  and  opened 
for  traffic  in  1871  ;  and  the  effect  of  its  opening  was 
to  change  the  port  for  the  transmission  of  the  Indian 
mails  from  Marseilles  to  Brindisi,  as  this  latter  route 
caused  a  saving  of  distance  of  103  miles  between  Lon- 
don and  Alexandria.  There  was,  moreover,  a  saving 
of  time  by  the  new  route,  owing  to  a  journey  by  land 
being  substituted  for  a  portion  of  the  sea  route,  as  trains 
travel  faster  than  steamers.  Altogether,  the  saving  of 
time  effected  by  the  change  of  route  amounted  to  forty- 
two  hours  in  the  transit  between  London  and  Alexandria. 
The  Mont  Cenis  and  the  Brenner  railways  traverse  the 
Alps  near  the  extremities  of  the  principal  range,  pass- 
ing outside  Switzerland  on  each  side,  and  afford  railway 
access  to  Italy  from  Western  and  Central  Europe. 

St  Gothard  Railway. — During  the  construction  of 
the  Mont  Cenis  Railway,  four  schemes  were  brought 
forward  for  another  Alpine  railway,  intermediate  between 
the  Brenner  and  the  Mont  Cenis.  The  four  routes  pro- 
posed followed  approximately  the  line  of  the  passes  of 
the  Simplon,  the  St  Gothard,  the  Lukmanier,  and  the 

C 


34  Course  of  St  Gothard  Railway. 

Splugen.  The  Germans  were  naturally  anxious  to  have 
a  more  direct  route  to  Italy,  and  to  avoid  having  to 
traverse  a  considerable  distance  in  French  territory  on 
the  one  hand,  or  in  Austrian  territory  on  the  other; 
and  Switzerland  was  desirous  to  secure  the  accommoda- 
tion of  an  Alpine  railway.  All  the  routes  involved  the 
construction  of  a  long  tunnel  at  the  summit ;  but  the 
St  Gothard  was  the  most  central  between  the  Mont 
Cenis  and  the  Brenner,  and  was  consequently  given  the 
preference,  both  by  Switzerland,  which  it  traverses 
centrally  in  its  widest  part,  and  by  Germany,  which 
thereby  has  direct  access  to  Italy,  without  passing 
through  any  other  foreign  country  than  Switzerland. 

On  approaching  the  south-eastern  end  of  the  Lake 
of  Lucerne,  by  Fluelen  and  Altorf,  the  traditional  scenes 
of  the  legendary  exploits  of  William  Tell,  the  scenery 
becomes  grander,  and  the  country  more  rugged. 
The  wild  gorges  of  the  valley  of  the  Reuss  torrent, 
encircled  as  they  are  with  a  halo  of  romance,  formed 
a  suitable  commencement  for  the  first  Swiss  trans-alpine 
railway,  which,  from  the  novel  method  by  which  the 
difficulties  of  the  steep  slopes  of  the  St  Gothard  Pass 
have  been  surmounted,  is  the  most  interesting  of  the 
group.  The  St  Gothard  Railway  does  not  rise  to  the 
same  elevation  as  the  Mont  Cenis;  and,  unlike  the  Mont 
Cenis,  the  levels  of  the  open  portions  at  the  entrances 
to  the  summit  tunnel  on  each  side  are  not  very  different. 
The  railway,  however,  commences  its  ascent  at  a  lower 
level  than  the  Mont  Cenis,  on  both  sides.  It  rises 
2077  feet  on  the  northern  slope,  in  the  17^  miles  between 
Erstfield  and  Goeschenen,  at  the  northern  extremity 
of  the  summit  tunnel,  and  2785  feet,  in  the  28^  miles 
between  Biasca  and  Airolo,  on  the  southern  slope. 


Loops  and  Spirals  on  Railway.  35 

(See  page  30.)  Owing  to  the  steepness  of  the  northern 
slope,  in  the  I4f  miles  between  Amstag  and  Goeschenen, 
the  heavy  average  gradient  of  I  in  42$  could  not  be 
obtained  without  lengthening  the  line,  and  thus  easing 
the  gradient,  by  a  spiral  and  two  long  parallel  loops 
near  Wasen.  (See  diagram.)  This  spiral  was  accom- 
plished by  making  the  rising  line  enter  a  curved  tunnel, 
and,  by  a  continuous  curve  and  ascent,  eventually  pass 
over  the  spot  again  which  it  had  traversed  in  tunnel 
at  a  lower  level.  The  double  open  loop  added  still 

ST  GOTHAB.D  RAILWAY. 

LOOPS  AND     SPIRALS    NEAR     WAfcEN. 


more  to  the  length  than  the  spiral,  and  was  effected 
by  gradually  rising  along  one  side  of  the  valley  till  a 
projecting  ridge  was  reached  on  which  the  line  could 
wind  round  in  tunnel,  and  crossing  the  valley,  rise 
on  the  opposite  side  in  a  reverse  direction  till  another 
ridge  afforded  an  opportunity  for  curving  back  and 
retracing  its  steps,  at  a  higher  level,  up  the  slope, 
The  length  of  the  loops  is  nearly  2  miles,  so  that 
an  additional  length  of  about  4  miles  was  gained  by  this 


36  Gradients  and  Curves  on  St  Got  hard  Railway. 

process  of  doubling  back.  Though  the  average  slope 
on  the  southern  side  was  not  so  steep  as  on  the 
northern  side,  four  spirals  were  adopted  for  easing 
the  gradient  at  steep  places.  These  loops  and  spirals, 
combined  with  the  general  rugged  nature  of  the 
valleys,  involved  the  construction  of  twenty-one  tunnels 
on  the  northern  slope,  and  twelve  tunnels  on  the 
southern  slope,  with  a  total  length  of  9^  miles. 
Accordingly,  with  the  long  tunnel  at  the  summit,  one- 
third  of  the  whole  length  of  56  miles  between  Erst- 
field  and  Biasca  is  in  tunnel.  The  maximum  gradient 
on  the  St  Gothard,  of  I  in  37,  is  slightly  easier  than 
the  worst  on  the  Mont  Cenis  ;  but,  owing  to  the  spirals 
and  loops,  the  curves  are  sharper  and  more  continu- 
ous, curves  of  14  chains  (308  yards)  radius  occupying 
a  length  of  nearly  3  miles,  and  curves  of  less  than  20 
chains  (440  yards)  extending  over  15!  miles.  Curves, 
indeed,  of  30  chains  (660  yards)  radius  and  less 
occupy  altogether  24  miles  out  of  the  46!  miles  of 
railway,  exclusive  of  the  summit  tunnel,  showing  what 
tortuous  windings  railways  in  mountainous  districts  re- 
quire to  keep  down  the  gradients  within  practicable 
limits.  The  works  were  commenced  in  1872,  and  the 
line  was  opened  for  traffic  in  1882  ;  but  in  this  case, 
as  with  the  Mont  Cenis,  the  duration  of  the  works 
mainly  depended  on  the  period  required  for  execut- 
ing the  summit  tunnel.  The  opening  of  the  St 
Gothard  route  drew  a  good  deal  of  the  traffic  to 
Belgium  and  Germany  which  previously  passed  through 
France,  and  by  the  Mont  Cenis  route,  thus  somewhat 
seriously  affecting  French  traffic  and  trade.  Conse- 
quently, fresh  schemes  have  been  proposed  for 
another  Alpine  railway  calculated  to  bring  back  some 


Proposed  Siwiplon  Railway.  37 

of  this  traffic  into  France.  The  route  which  has  found 
most  favour  is  across  the  Simplon,  which  would  both 
shorten  the  distance  between  Calais  and  Brindisi,  and 
also,  by  keeping  to  a  level  even  lower  than  the 
Semmering  Railway,  would  reduce  the  cost  of  traction 
and  improve  the  rate  of  transit.  The  Simplon  route 
would  approach  the  St  Gothard  Railway  towards  the 
south,  as  it  would  run  direct  to  Milan,  like  the  St 
Gothard  ;  but  this  would  not  be  an  objection  to  a  line 
competing  with  the  St  Gothard  for  traffic.  The  traffic  on 
the  existing  lines  would  not  justify  the  heavy  expendi- 
ture required  for  a  fourth  line  across  the  Alps  to  Italy, 
on  commercial  grounds  alone ;  but  the  French  might 
support  the  scheme  on  account  of  its  national  import- 
ance, for  bringing  back  to  France  some  of  its  lost  traffic 
and  trade  ;  and  it  would  improve  the  communications 
of  Italy  and  Switzerland  with  Northern  Europe.  The 
Simplon  approach  railways,  however,  to  the  summit 
tunnel  would  be  simpler  and  shorter  than  those  of  the 
St  Gothard  ;  and  in  order  to  find  a  parallel  to  the  loops 
and  spirals  of  the  St  Gothard  Railway,  it  is  necessary 
to  turn  to  the  railways  of  another  hemisphere. 

Ar/berg  Railway. — One  more  Alpine  railway  deserves 
a  brief  notice  before  leaving  the  Alps  for  the  Rocky 
Mountains,  as,  though  less  known  than  the  others,  it 
involved  works  little  inferior  to  those  of  the  Mont  Cenis, 
and  it  attains  an  elevation  surpassed  only  in  that 
region  by  the  Brenner  and  the  Mont  Cenis.  The 
Austrian  Government,  for  the  third  time,  undertook  the 
construction  of  an  Alpine  railway,  passing  through  the 
Arl  mountain,  for  the  purpose  of  connecting  France 
with  Austria,  across  Switzerland  alone.  The  railway 


38  Course  of  the  Arlberg  Railway. 

runs  from  Innsbruck  to  Bludenz ;  but  the  mountain 
portion  only  commences  at  Landeck,  44-^  miles  from 
Innsbruck,  ascending  1721  feet  in  \*j\  miles  on  the  east 
slope,  and  2158  feet  in  i6f  miles  on  the  west  slope 
before  entering  the  summit  tunnel.  The  ascent  on  the 
west  side  is  steeper  than  on  any  of  the  other  Alpine 
lines,  and  it  also  has  the  steepest  gradient,  of  I  in  32^-. 
The  sharpest  curves  on  this  line,  of  10  chains  (220  yards) 
radius,  are  but  slightly  exceeded  by  the  Semmering  ;  and 
the  length  of  over  9  miles  of  curves  not  exceeding  14  chains 
(308  yards)  in  radius,  places  the  Arlberg  Railway  in  a 
worse  position  in  this  respect  than  the  other  lines.  The 
greatest  height  in  the  open,  of  4270  feet  above  sea  level, 
is  attained  at  the  western  entrance  to  the  summit  tunnel, 
so  that  fortunately,  as  in  the  other  cases,  the  greatest 
elevation  occurs  on  the  warmer  side  of  the  ridge. 
This  elevation  is  514  feet  higher  than  the  St  Gothard, 
and  only  227  feet  lower  than  the  summit  of  the  Brenner 
Railway. 


RAILWAYS  ACROSS   THE   ROCKY   MOUNTAINS. 

The  mountain  railways  of  America  have  been  con- 
structed under  different  conditions  to  those  across  the 
Alps.  The  Alpine  railways  of  the  Brenner,  the  Mont 
Cenis,  and  St  Gothard,  were  made  in  order  to  obtain 
a  quicker  and  more  direct  route  from  Northern  Europe 
to  Italy  and  the  port  of  Brindisi ;  and  they  had  to  be 
so  laid  out  as  to  be  always  open  except  in  quite  excep- 
tionally severe  weather,  and  to  be  run  over  at  a  fair 
speed.  Moreover,  the  choice  of  route  was  restricted  to 
three  or  four  passes  ;  and  the  St  Gothard  Railway  had 


Traversing  the  Rocky  Mountains.  39 

to  be  designed  so  as  to  compete  for  traffic  with  the 
previous  lines.  When,  however,  railway  connection  with 
the  far  west  of  the  United  States  became  expedient, 
for  the  development  of  that  very  extensive  district, 
necessitating  the  passage  of  the  Rocky  Mountains,  it 
was  important  that  the  railways  should  be  made  as 
economically  as  possible  in  the  first  instance,  leaving 
improvements  to  be  effected  as  soon  as  the  amount  of 
traffic  permitted.  The  choice  of  route  was  quite  un- 
restricted in  an  unsettled  country ;  and  a  reduction  in 
first  cost  was  of  much  greater  consequence,  on  a  line 
with  little  traffic  at  first,  than  low  working  expenses  and 
high  speeds.  Moreover,  in  America,  the  blocking  of 
trains  by  snow  in  winter  is  a  more  common  event ;  a 
regular  system  of  clearing  the  lines  by  snow  ploughs  is 
in  use ;  and  a  temporary  stoppage  of  the  traffic  in  winter 
between  the  east  and  west  is  of  less  importance  than 
along  through  routes  in  Europe  to  distant  parts  of  the 
world.  Consequently,  high  elevations,  more  subject  to 
snow  than  the  highest  limits  of  the  Alpine  railways, 
may  be  traversed  in  America.  This  is,  in  fact,  the  only 
method  of  carrying  railways  across  the  Rocky  Mountains ; 
for,  besides  the  prohibitive  cost  of  constructing  long 
tunnels  for  pioneer  railways,  these  ranges,  though  not 
higher  than  the  Alps,  have  a  very  much  greater  width, 
and  could  not  therefore  be  similarly  pierced  at  a  moderate 
elevation. 

United  States  Western  Railways. — There  are  three 
main  lines  traversing  the  western  portion  of  the  United 
States,  and  extending  to  the  Pacific  Ocean,  namely, 
the  Union  or  Central  Pacific,  which  was  the  first  line 
constructed  across  the  Rocky  Mountains,  and  was 


4O  Routes  of  Pacific  Railways. 

opened  in  1869;  the  Northern  Pacific,  further  north, 
commenced  in  1870,  and  completed  in  1883  ;  and  the 
Southern  Pacific,  to  the  south,  constructed  during  the 
same  period.  New  York  is  in  direct  connection  with 
these  three  lines ;  and  the  route  from  New  York  to 
Pittsburg  is  common  to  them  all.  At  Pittsburg  two 
main  lines  branch  off,  one  going  westwards  to  Chicago, 
and  the  other  south-west  to  St  Louis.  The  Northern 
Pacific  and  the  Union  Pacific  branch  off  from  Chicago, 
the  one  going  north-west  to  Portland,  and  the  other 
to  the  west,  past  Omaha,  Ogden,  and  the  Salt  Lake, 
and  then  turning  southwards  to  San  Francisco.  The 
Southern  Pacific  is  reached  from  St  Louis,  and  passing 
through  Indian  Territory,  part  of  Texas,  and  New 
Mexico  near  the  Mexican  boundary,  it  proceeds  by 
Mojave  to  Los  Angelos,  and  towns  on  the  Pacific  coast, 
with  a  northern  branch  from  Mojave  to  San  Francisco. 
There  is  a  fourth  line,  the  Atlantic  and  Pacific,  which 
appears  to  have  been  intended  to  run  nearly  parallel 
to,  but  a  good  deal  north  of  the  Southern  Pacific,  from 
St  Louis  to  Mojave  Junction,  by  Vinita  and  Al- 
buquerque. Though,  however,  the  line  is  constructed 
from  Albuquerque  to  Mojave,  there  is  a  gap  left  be- 
tween Sapulpa,  a  little  beyond  Vinita,  and  Albuquerque, 
so  that  passengers  by  the  Atlantic  and  Pacific  Railway 
have  to  make  a  detour  from  St  Louis,  by  Kansas, 
Dodge  City,  and  Santa  Fe,  to  Albuquerque.  The 
fragment  of  a  through  line  from  St  Louis,  which 
terminates  at  Sapulpa,  has  the  grand,  but  misleading, 
title  of  the  St  Louis  and  San  Francisco  Railway; 
whereas  travellers  by  it  would  be  landed  on  the 
Arkansas  River,  in  the  middle  of  the  Indian  Territory, 
with  part  of  Texas  and  more  than  half  of  New 


Elevation  of  the  Union  Pacific.  41 

Mexico   between   them  and    Albuquerque,  the   point  of 
commencement  of  the  Atlantic  and  Pacific  Railway. 

The  Union  or  Central  Pacific  Railway  reaches  its 
highest  elevation,  of  8248  feet  above  sea  level,  in  travers- 
ing the  Rocky  Mountains,  at  Sherman's  Pass,  on  the 
eastern  edge  of  the  ridge  ;  and  after  passing  across  a  high 
table  land,  with  a  minimum  elevation  of  6112  feet,  it 
rises  over  the  Aspen  Pass,  on  the  western  edge,  to  a 
height  of  7546  feet.  (See page  30.)  It  then  traverses 
the  table  land  between  the  Rocky  Mountains  and  the 
Sierra  Nevada,  having  an  elevation  of  3897  feet  at  its 
lowest  point ;  and  after  crossing  the  ridge  of  the  Sierra, 
at  a  height  of  7021  feet,  it  descends  rapidly  towards 
the  western  coast  to  Sacramento,  about  140  miles  from 
San  Francisco.  For  a  distance  of  440  miles  across  the 
Rocky  Mountains,  the  railway  never  descends  within 
1600  feet  of  the  highest  altitude  of  the  Brenner  Railway, 
which  attains  the  highest  elevation  of  all  the  Alpine 
railways ;  and  from  the  eastern  slope  of  the  Rocky 
Mountains  to  the  western  slope  of  the  Sierra  Nevada, 
a  distance  along  the  line  of  1300  miles,  the  railway  is 
never  lower  than  no  feet  above  the  summit  level  of  the 
St  Gothard  Railway.  This  immense  stretch  of  high 
land,  across  a  mountain  range  whose  peaks  do  not 
reach  the  elevation  of  the  higher  Alpine  peaks,  shows 
how  totally  different  the  conditions  are  for  the  construc- 
tion of  a  railway  across  the  Rocky  Mountains  to  those 
of  the  Alpine  lines.  Though  the  maximum  elevation 
reached  is  about  the  level  of  perpetual  snow  in  the 
Alps,  and  within  750  feet  of  double  the  elevation 
attained  by  the  Brenner  Railway,  there  is  a  very  long, 
gradual  ascent  on  the  eastern  side  for  500  miles  from 
Omaha ;  and  the  steep  gradients  are  mainly  confined 


42  Gradients  of  the  Union  Pacific. 

to  the  passage  of  the  ridges  at  each  edge  of  the  Rocky 
Mountains,  and  the  Sierra  Nevada,  the  longest  and 
steepest  gradient  being  the  descent  from  this  latter 
ridge  to  the  low  land  near  the  Pacific  coast.  This 
descent,  from  the  summit  to  a  place  25  miles  short  of 
Sacramento,  is  6545  feet  in  a  distance  of  80  miles,  with  a 
maximum  gradient  of  I  in  45^,  and  an  average  gradient 
of  i  in  64.  The  steepest  part  of  the  ascent,  from  the 
east  to  the  highest  point  at  Sherman's  Pass,  is  only 
a  rise  of  2204  feet  in  33  miles,  with  a  maximum 
gradient  of  I  in  66 ;  whilst  a  steeper  though  shorter 
ascent  leads  to  the  summit  on  the  eastern  side  of  the 
Sierra  Nevada,  where  the  rise  is  1005  feet  in  I3f  miles, 
with  a  maximum  gradient  of  I  in  50.  The  line  is 
necessarily  very  much  curved  in  threading  its  way 
through  this  vast  mountainous  region,  so  as  to  obtain 
satisfactory  gradients,  the  curved  portion  of  this  section 
of  the  line  attaining  a  total  length  of  870  miles,  whilst 
the  sharpest  curves  have  a  radius  of  8|  chains  (193 
yards). 

The  Northern  Pacific  and  Southern  Pacific  railways 
cross  the  Rocky  Mountains  where  this  range  is  less 
broad  and  less  high  than  along  the  line  of  the  Central 
Pacific  Railway  ;  and  they  also  escape  having  to  cross 
a  second  ridge  near  the  Pacific  Ocean,  and  therefore 
avoid  steep  gradients  on  the  west  slope  as  well  as  the 
east.  The  Northern  Pacific  Railway  reaches  its  maxi- 
mum altitude,  of  about  5800  feet  above  sea  level,  in 
crossing  the  western  ridge  of  the  Rocky  Mountains  at 
Deerlodge  Pass,  and  the  Southern  Pacific  in  crossing 
the  eastern  ridge,  at  a  height  of  about  5720  feet.  The 
steepest  ascents  on  these  lines  are  a  rise  of  1668  feet 
in  about  14^  miles,  with  a  gradient  of  I  in  45^,  on 


The  Northern,  Southern,  and  Central  Pacific.  43 


the  Northern  Pacific,  and  a  rise  of  2674  feet  in 
miles,  with  a  similar  maximum  gradient,  on  the  Southern 
Pacific.  This  latter  railway  has  a  spiral  tunnel,  about 
three-quarters  of  a  mile  long,  similar  to  the  St  Gothard 
tunnels  ;  and  its  sharpest  curves  have  a  radius  of  8| 
chains  (193  yards),  like  the  Central  Pacific.  The 
tunnels  on  all  these  western  lines  nowhere  attain  a  mile 
in  length. 

The  Central  Pacific  Railway  is  pre-eminent  amongst 
the  Pacific  main  lines,  both  in  the  elevation  reached, 
and  in  the  altitude  it  has  to  maintain  for  such  a  great 
distance,  together  with  the  long  and  rapid  descent  it 
has  to  make  towards  the  western  coast,  owing  to  the 
configuration  of  the  mountain  ranges  at  the  latitude 
which  it  follows.  All  the  three  lines  attain  heights 
considerably  in  excess  of  those  reached  by  any  Alpine 
railway  ;  and  whereas  their  gradients  are  better  than 
those  found  necessary  in  the  Alps,  their  curves  are 
sharper.  The  system  of  pivoting  each  car  on  two 
bogies,  with  a  small  wheel-base,  employed  in  the  United 
States,  enables  the  trains  to  run  easily  and  safely  round 
sharp  curves,  especially  at  the  moderate  speed  adopted 
on  the  western  lines  ;  and  the  use  of  sharp  curves 
reduces  the  cost  of  construction,  and  also  the  maxima 
gradients,  which  is  of  considerable  importance  where 
the  ascending  gradients  are  continuous  for  very  long 
distances. 

Some  of  the  branch  3-foot  gauge  lines  near  Denver 
present  even  more  remarkable  features  than  the  main 
western  lines,  though  on  a  smaller  scale.  Thus  a 
branch  of  the  Denver  and  Rio  Grande  line  rises  3675 
feet  in  25  miles,  with  a  maximum  gradient  of  I  in  25, 
and  with  curves  having  a  minimum  radius  of  3f  chains  (80 


44  Features  of  Denver  Railways. 

yards) ;  and  it  reaches  an  elevation  at  the  Marshall  Pass 
of  10,850  feet.  (See page  30.)  The  Calumet  Mine  branch 
rises  about  2700  feet  in  7  miles,  with  a  gradient  of  I  in 
I2|-,  and  curves  having  a  minimum  radius  of  3^-  chains 
(77  yards),  and  is  the  steepest  line  worked  by  ordinary 
locomotives.  On  the  Georgetown  branch  there  is  a  spiral 
where  the  railway  curves  round  and  crosses  over  its  own 
track,  on  a  viaduct,  at  an  elevation  of  75  feet  above  its 
former  level.  It  is  also  on  one  of  these  lines  that  the 
railway,  in  crossing  a  deep  canon,  emerges  directly  from  a 
tunnel  on  to  a  bridge,  without  any  parapet,  spanning  the 
perpendicular  chasm,  so  that  passengers,  on  emerging, 
straight  from  the  darkness  on  to  an  unseen  bridge, 
feel  as  if  the  train  had  suddenly  leapt  into  a  fathom- 
less abyss. 

Canadian  Pacific  Railway. — A  fourth  railway  tra- 
verses North  America,  along  the  southern  portion  of 
Canada,  connecting  Montreal,  on  the  St  Lawrence,  with 
Vancouver,  on  the  Pacific,  opposite  Vancouver  Island. 
This  railway,  accordingly,  which  passes  by  Winnipeg, 
affords  direct  communication  by  rail  and  steamer 
between  the  east  of  Canada  and  China  and  Australia. 
The  Canadian  Pacific  Railway,  which  was  completed 
in  1885,  and  opened  in  1886,  ascends  gradually,  on 
the  eastern  side,  to  Stephen's  Pass  on  the  Rocky 
Mountains,  5296  feet  above  the  sea,  the  highest  point 
of  the  railway,  rising  1921  feet  in  123  miles.  (See 
page  30.)  It  then  descends  rapidly  on  the  western  slope 
of  the  range,  where  the  maximum  gradient,  of  i  in  22^, 
occurs,  4  miles  long,  along  a  temporary  portion  of 
line,  for  which  another  route,  with  the  authorised 
maximum  gradient,  of  I  in  45^,  is  to  be  eventually 


Course  of  Canadian  Pacific  Railway.         45 

substituted.  From  the  summit  to  the  western  base  of 
the  Rocky  Mountains,  the  railway  descends  2742  feet 
in  43  miles,  and  then  traverses  the  fairly  level  table 
land  between  the  Rocky  Mountains  and  the  Selkirk 
range,  having  an  average  elevation  of  about  2500  feet. 
The  railway  then  rises  1920  feet  in  18  miles,  to  surmount 
the  Selkirk  range  at  an  elevation  of  4300  feet  above 
sea  level,  and  descends  2830  feet,  on  the  western  slope, 
in  47  miles.  The  curves  have  a  minimum  radius  of  8f 
chains  (190  yards).  The  Canadian  Pacific  Railway, 
accordingly,  resembles  the  Central  Pacific '  Railway  in 
having  to  surmount  two  distinct  ranges ;  but  the  eleva- 
tion and  width  of  the  ranges  are  considerably  less  on  the 
Canadian  Pacific.  Owing,  however,  to  the  high  latitude 
of  over  50°  of  this  northern  line,  the  summit  of  the 
line  is  only  about  1000  feet  below  the  line  of  perpetual 
snow.  Nevertheless,  no  protection  has  been  required 
for  the  line,  in  the  passage  of  the  Rocky  Mountains, 
against  snow  drifts  and  avalanches  ;  but  at  the  crossing 
of  the  Selkirks,  in  consequence  of  the  much  greater  falls 
of  snow  on  the  Pacific  side,  it  has  been  found  necessary 
to  erect  a  number  of  snow  sheds  at  places  along  the 
upper  part  of  the  eastern  slope  and  more  than  half 
way  down  the  western  slope.  The  tunnels  on  the 
Rocky  Mountain  section  of  the  line  are  quite  short. 

One  feature  about  all  these  western  lines  is  the 
large  employment  of  wood  for  bridge  construction,  and 
trestles  for  viaducts,  owing  to  timber  being  so  often 
found  on  the  spot ;  and  these  erections,  in  the  older 
lines,  have  frequently  been  replaced  in  time  by  more 
durable  and  lighter  structures  in  iron,  with  greater 
spans.  Timber  viaducts  are  also  sometimes  substituted 
for  embankments,  in  order  to  save  time  in  construction, 


46  Ascent  of  Railway  to  Mexico. 

cheapness  and  rapidity  of  construction  being  the  main 
objects  sought  in  these  lines  which  open  up  undeveloped 
countries. 

Mexican  Railway. — The  railway  from  Vera  Cruz  to 
the  City  of  Mexico,  commenced  in  1864  and  opened  in 
1872,  rises  from  the  sea  level,  on  the  Atlantic  coast,  to  a 
height  of  over  8000  feet,  in  order  to  reach  the  high,  wide 
plateau  on  which  the  City  of  Mexico  is  situated  ;  and 
this  ascent  has  to  be  accomplished  in  the  first  107  miles, 
out  of  a  total  length  of  line  of  263  miles.  (See 
page  30.)  The  principal  portion  of  the  ascent,  amount- 
ing to  6400  feet,  is  effected  in  the  54  miles  between 
Atoyac  and  the  edge  of  the  plateau,  with  an  average 
rise  of  I  in  44^,  and  a  maximum  gradient  of  I  in  25. 
Even  to  obtain  these  gradients,  the  line  has  to  wind  about, 
forming  three  or  four  open  loops,  with  curves  having  a 
minimum  radius  of  5  chains  (no  yards).  As  soon  as  the 
edge  of  the  plateau  is  reached,  at  Boca  del  Monte,  the 
railway  follows  a  circuitous  but  tolerably  level  course, 
descending  a  little  to  Mexico.  The  steep  part  of  the 
line  is  worked  by  Fairlie  engines  (page  56),  which  type 
was  first  used  on  the  Festiniog  Railway,  with  a  2-foot 
gauge.  This  line  ascends  to  about  the  same  elevation 
as  the  Central  Pacific  Railway;  but  though  the  moun- 
tainous portion  of  the  line  is  a  good  deal  shorter,  it 
has  both  steeper  gradients  and  sharper  curves  than  the 
Central  Pacific. 


RAILWAYS   ACROSS   THE   ANDES. 

Peruvian     Railways.  —  Though     railway      enterprise 
might   appear    to   have   reached   its   limit   in   traversing 


Railways  Surmounting  the  Andes.  47 

the  Rocky  Mountains,  and  in  reaching  an  altitude  of 
10,852  feet  at  the  Marshall  Pass,  still  more  formidable 
obstacles  have  been  surmounted  and  greater  elevations 
attained  in  ascending  the  Peruvian  Andes.  The  Andes 
form  a  continuous  mountain  chain  along  the  western 
side  of  South  America,  as  the  Rocky  Mountains  do 
in  North  America  ;  but  they  rise  higher,  and  approach 
in  places  nearer  to  the  coast.  One  railway  connects 
Mollendo,  a  port  on  the  Pacific,  with  Arequipa,  situated 
7560  feet  above  sea  level ;  it  is  107  miles  in  length,  and 
was  completed  in  1870.  This  railway  has  been  pro- 
longed from  Arequipa,  up  the  Andes,  to  Puno,  on  the 
shore  of  Lake  Titicaca,  on  the  other  side  of  a  ridge 
which  it  crosses,  in  a  shallow  cutting,  at  an  elevation  of 
14,660  feet  above  the  sea.  (See  page  30.)  The  line  was 
completed  as  far  as  Puno  in  1874,  situated  at  an  altitude  of 
about  12,000  feet  above  sea  level,  and  is  to  be  prolonged 
to  Cuzco,  to  the  north-west  of  Puno.  For  a  portion  of  the 
ascent,  the  gradient  is  I  in  25,  by  means  of  which  the  line 
rises  about  4500  feet  Since  the  construction  of  the  railway 
steamers  have  been  placed  on  Lake  Titicaca,  and  thus 
place  Bolivia  in  communication  with  this  line  and  with 
the  Pacific  Ocean. 

Another  still  bolder  railway  was  commenced,  in 
1870,  by  an  American  engineer,  for  connecting  Lima, 
the  capital,  with  Oroya,  situated  on  the  eastern  slope 
of  the  Andes,  at  an  elevation  of  12,178  feet.  It 
starts  from  Callao,  the  port  of  Lima;  and  for  the 
first  33^  miles,  up  to  Chosica,  it  rises  with  compara- 
tively moderate  gradients,  not  exceeding  I  in  40,  to 
a  height  of  2800  feet.  (See  page  30.)  After  pass- 
ing Chosica,  the  country  becomes  more  rugged,  and 
the  line  rises  with  gradients  of  I  in  25,  following  the 


48  Oroya  Railway  over  the  Andes. 

winding  course  of  the  gorge  through  which  the  Rimac 
river  flows,  which  is  crossed  by  the  Capiche  bridge. 
The  increasing  rise  of  the  valley  of  the  Rimac,  on  reach- 
ing San  Bartolome,  46!  miles  from  the  coast,  at  an 
altitude  of  4900  feet,  has  necessitated  the  introduction 
of  switchbacks  in  places  between  this  point  and  the 
summit,  together  with  long  loops,  making  the  railway 
retrace  its  steps  at  a  higher  level,  combined  with  curves 
having  a  minimum  radius  of  6  chains  (132  yards),  in 
order  not  to  exceed  the  maximum  gradient  of  I  in 
25.  A  switchback  is  a  sort  of  siding,  up  to  which 

OROYA   RAILWAY,    PERU. 
SWITCHBACKS  AND  LOOPS 


So  ALE. 

the  train  is  drawn  ;  and  the  train  is  then  shunted  in 
the  reverse  direction,  and  pushed  by  the  engine,  which 
is  now  at  the  back  of  the  train,  up  a  line  following 
a  higher  slope ;  and  thus,  by  a  series  of  zigzags, 
the  train  rises  up  the  steep  mountain  sides  to  a 
higher  elevation.  (See  diagram.}  After  passing  San 
Bartolome'  the  switchbacks  begin,  and  the  line  crosses 
and  recrosses  the  river  Seco  ;  and  after  passing  through 
two  tunnels,  it  crosses  a  deep  gorge  on  the  Verrugas 
Viaduct,  a  light -looking  structure,  573  feet  long, 
supported  on  three  piers,  at  a  maximum  height  of 
over  250  feet  above  the  bottom  of  the  ravine.  The 


Difficulties  of  Oroya  Railway.  49 

railway  then  winds  about,  with  gradients  of  i  in  25, 
passing  through  tunnels  whose  entrances  may  be  de- 
scried at  different  altitudes  up  the  steep  slope  ;  and  it 
then  passes  across  the  Challapa  gorge,  on  a  bridge 
raised  160  feet  above  the  bottom  of  the  gorge.  Matucana, 
which  is  reached  at  62^  miles  from  the  coast,  is  only 
27  miles  from  the  summit  of  the  railway  in  a  direct 
line ;  but  a  devious  course  of  42^  miles  has  to  be 
traversed  to  overcome  the  difficulties  of  the  ascent, 
without  exceeding  the  gradient  of  I  in  25.  At  this 
part  of  the  line,  about  half  way  up  the  ascent,  the  cliffs 
encountered  on  the  route  are  so  precipitous  that  work- 
men had  to  be  lowered  by  ropes  from  ledge  to  ledge, 
cut  out  of  the  side  of  the  cliff,  till  the  railway  level 
was  reached.  The  engineers,  also,  had  to  be  conveyed 
from  one  side  of  the  deep  ravines  to  the  other,  in  slings 
hung  to  a  wire  cable  stretched  across  at  the  top.  In 
a  distance  of  15  miles,  between  Tambo  de  Viso  and 
Anchi,  the  railway  passes  through  twenty-two  tunnels  ; 
and,  between  Anchi  and  San  Mateo,  the  Los  Infernillos 
canon  has  to  be  crossed  where  the  river  Rimac  passes 
between  cliffs  of  red  porphyry  rising  perpendicularly  to 
a  height  of  1500  feet.  The  railway,  on  emerging  from 
a  tunnel  through  one  of  the  cliffs,  traverses  a  bridge 
spanning  the  chasm  at  a  height  of  165  feet  above  the  bed 
of  the  river,  and  then  enters  a  tunnel,  through  the  opposite 
cliff,  resembling  the  crossing  of  a  canon  on  the  Denver 
and  Rio  Grande  Railway  previously  alluded  to.  The  loops 
and  zigzags  are  sometimes  so  frequent  that,  at  Chicla, 
five  parallel  lines,  three  on  one  side  and  two  on  the 
other  side  of  the  gorge,  are  visible  (see  diagram,  page  48), 
rising  one  above  the  other  to  a  considerable  height ;  whilst 
the  greatest  horizontal  distance  between  them  does 

D 


50  Peculiarities  of  Oroya  Railway. 

not  exceed  500  feet.  The  head  of  the  Rimac  gorge 
is  surrounded  by  such  precipitous  cliffs  that  the  railway 
has  to  traverse  them  by  means  of  seven  tunnels,  and 
then  proceeds,  through  a  desolate  snow-clad  region,  to 
the  summit  tunnel,  3847  feet  in  length,  which  pierces  a 
a  narrow  ridge.  The  summit  level  of  the  railway  is 
15,645  feet  above  the  sea,  higher  than  Monte  Rosa  or 
the  Matterhorn,  and  only  136  feet  lower  than  the  top 
of  Mont  Blanc,  and  about  three  and  a  half  times  the 
height  of  the  Brenner  Railway.  Moreover,  this  eleva- 
tion has  been  attained  in  104^  miles  from  the  coast, 
an  ascent  of  12,845  feet  having  been  accomplished  in 
a  distance  of  71  miles,  giving  an  average  rise  of  I  in 
29.  The  descent  to  Oroya,  on  the  other  side  of  the 
ridge,  is  only  3467  feet  in  a  distance  of  31 J  miles;  and 
the  total  length  of  the  line  is  136  miles.  As  Oroya  is 
situated  in  the  valley  of  the  Huallaga,  a  tributary  of 
the  Amazon,  on  which  steamers  run  from  the  Peruvian 
ports  on  its  banks  to  the  Brazilian  port  of  Tabatinga 
on  the  Amazon,  this  railway  opens  up  a  means  of 
communication  between  the  Pacific  and  Brazil.  This 
railway  is  quite  unique  in  the  rugged  character  of  the 
district  traversed,  the  difficulties  encountered,  the  length 
of  steep  gradients,  and  the  great  elevation  attained ;  and 
it  furnishes  the  most  remarkable  example  of  railway 
construction  in  the  world.  (Seepage  54  for  cost) 

Gradients,  in  proportion  to  their  steepness,  limit  the 
weight  of  the  train  that  a  locomotive  can  draw  up 
them ;  and  as  sharp  curves  have  a  similar  influence, 
the  steepest  gradient  and  sharpest  curve  on  a  line 
should  not  be  combined  if  possible.  Steep  gradients, 
however,  involve  less  cost  in  working  when  they  are 
concentrated  in  one  part  of  a  line  than  when  they  are 


Gradients  and  Curves  on  Railways.  5 1 

scattered,  for  an  auxiliary  engine  can  be  employed  at 
that  part.  When  two  or  three  heavy  gradients  occur 
at  different  places  on  a  line,  the  cost  of  working  the 
whole  line  may  have  to  be  increased  to  provide  for 
these  proportionately  short  pieces  of  line,  and  in  such 
cases  it  is  more  economical  to  make  a  detour  in  substi- 
tution for  the  shorter  and  steeper  line.  Moreover,  on 
mountain  lines,  it  is  preferable  to  reduce  the  cost  of 
the  works  by  sharpening  the  curves,  rather  than  by 
increasing  the  gradient  beyond  the  limit  adopted  on 
other  portions  of  the  line. 

The  western  part  of  South  America  offers  the 
greatest  difficulties  in  construction  of  any  country 
hitherto  penetrated  by  railways ;  whilst  the  central 
Pampas  adjoining  it,  with  immense  flat  plains,  affords 
remarkable  facilities  for  railway  extension. 

Railway  Progress. — Though  the  extension  of  rail- 
ways in  Great  Britain,  the  birthplace  of  the  railway 
system,  has  become  smaller  in  the  last  few  years,  rail- 
ways are  rapidly  progressing  in  other  parts  of  the 
world.  Thus,  in  Europe,  the  length  of  railways  has 
increased  from  96,170  miles  in  1877  to  129,126  miles 
in  1887,  of  which  increase  only  2501  miles  belonged 
to  the  United  Kingdom.  In  Asia,  the  increase  was 
from  7910  miles  in  1877  to  16,714  miles  in  1887,  of 
which  6757  miles  were  due  to  the  development  of 
railways  in  British  India.  In  Africa,  the  railways 
increased  in  length  from  1868  miles  in  1877  to  4794 
miles  in  1887,  the  greater  portion  of  the  increase 
having  occurred  in  the  Cape  Colony,  and  Algeria  and 
Tunis,  which  nearly  quadrupled  their  mileage  in  this 
period.  In  America,  the  railway  mileage  increased 


52  Development  of  Railways. 

from    91,910    miles    in    1877  to    180,398    miles  in    1887, 
in  which,  of  course,  the  United  States  are  far  ahead  of 
all    the   other   countries    put    together,   though   Canada, 
Mexico,    Brazil,   and    the    Argentine    Republic   show   a 
larger  proportionate    increase  in  this  period.      The  rail- 
ways in    Australasia,  during   the  same  period,  increased 
from    3471     miles    to    9505    miles.      The    total    railway 
mileage  in  the  world,  during  these  ten  years,  increased 
from  201,329  miles    to  340,539  miles,  or  an  increase  of 
about  sixty-nine  per  cent.     The  greatest  development  of 
railways  has  occurred  in  the  United   States,  where   the 
number  of  miles  open  for  traffic  rose  from  79,088  miles 
in  1877    to  149,281   miles   in   1887,  the  greatest  increase 
in    any   one    year,   amounting   to    12,872    miles,   having 
taken  place  in   1887.      The  increase    in    1888   was  6801 
miles,    raising    the     total    mileage    of   railways    in    the 
United    States,   at   the   end   of   1888,  to    156,082    miles, 
nearly   half  of   the   entire   mileage    of   railways    in    the 
world ;   and    it    was   doubled  in   the  twelve   years    from 
1876  to    1888.      The   number   of  passengers  carried  by 
railway  in  the  United  States  has  risen  from  289,000,000 
in    1882   to   451,000,000   in    1888,  these   numbers   being 
exclusive    of    the    very    numerous    passengers    on    the 
New  York   Elevated   Railway.     (See  page  22.) 

The  great  lines  crossing  North  America  from  east 
to  west  have  a  very  considerable  unbroken  length  ;  for 
the  Canadian  Pacific  Railway,  from  Montreal  to  Van- 
couver, traverses  2500  miles,  eight  times  the  distance  by 
rail  between  London  and  Penzance;  and  the  Union 
Pacific  Railway,  from  New  York  to  San  Francisco, 
runs  across  about  3200  miles  of  country,  or  more  than 
four  times  the  distance  from  London  to  Thurso,  the 
most  northern  station  in  Scotland.  The  average  speed 


Increase  of  Railway  Mileage.  53 

of  travelling  from  New  York  to  San  Francisco  is  about 
22  miles  an  hour,  including  stoppages ;  and  the  time 
occupied  in  the  transit  across  America  is  six  days  and 
nights.  A  large  number  of  miles,  also,  of  railway,  in- 
cluding their  own  system  and  other  lines,  are  worked 
over  by  some  of  the  large  railway  companies  in 
the  United  States,  for  6288  miles  are  worked  by  the 
Union  Pacific  Railway  Company,  and  5932  miles  by 
the  Southern  Pacific. 

Since  1850  the  growth  of  the  railway  system  has 
been  enormous,  though  at  that  period  a  quarter  of 
a  century  had  elapsed  since  its  inauguration  by  the 
opening  of  the  Manchester  and  Liverpool  Railway. 
The  total  number  of  miles  of  railway  opened  for  traffic 
throughout  the  world  was  only  24,015  miles  in  1850, 
or  about  double  the  mileage  which  the  United  States 
alone  added  to  their  railway  system  in  1887.  This 
mileage  had  risen  in  1860  to  67,002  miles;  in  1870 
to  129,874  miles,  only  slightly  in  excess  of  the  mileage 
reached  by  Europe  about  seventeen  years  later ;  and 
in  1880  to  229,635  miles.  Assuming  the  average  rate 
of  yearly  increase  between  1880  and  1887  to  have  been 
maintained,  the  total  length  of  railways  in  the  world  will 
have  reached  about  388,000  miles  at  the  close  of  1890, 
making  a  total  extension  of  364,000  miles  of  railways  in 
the  last  forty  years.  Statistics,  however,  show  what  vast 
areas  are  still  devoid  of  railway  accommodation  in  Asia, 
Africa,  South  America,  and  Australasia ;  and  of  all 
the  countries  in  the  world,  China,  with  its  vast  extent 
and  teeming  population,  and  with  only  28  miles  of 
railway  open  in  1887,  should,  as  soon  as  the  prejudices 
of  its  rulers  have  been  removed,  take  the  lead  in  the 
future  development  of  railways. 


CHAPTER    III. 

NARROW  GAUGE,  FELL,  RIGI,  PILATUS   AND  ABT 
MOUNTAIN  RAILWAYS. 

RAILWAYS  in  mountainous  districts  are  very  costly  in 
construction,  even  when  they  do  not  involve  the 
making  of  the  long  tunnels  at  the  summit,  for  which 
the  Alpine  railways  are  celebrated.  Taking,  for  in- 
stance, the  Peruvian  railways  described  in  the  last 
chapter,  where  there  are  no  long  tunnels,  and  the 
expenditure  has  been  kept  down,  as  far  as  practicable 
in  such  rugged  country,  by  very  steep  gradients  and 
sharp  curves,  the  line  from  Arequipa  to  Puno  cost 
£18,730  per  mile,  and  the  line  from  Callao  to  Oroya 
cost  £31,960  per  mile.  Accordingly,  engineers  have 
endeavoured  to  devise  expedients  for  reducing  the  cost 
of  construction,  so  as  to  extend  railways  to  places  out 
of  the  through  lines  of  communication,  or  to  parts 
where  the  prospects  of  traffic  do  not  warrant  a  large 
expenditure. 

Narrow  Gauge  Railways. — A  smaller  distance 
between  the  rails  than  the  standard  gauge  of  4  feet 
8J-  inches  has  been  adopted  in  several  cases,  with  the 
object  of  reducing  the  first  cost ;  and  this  system  has 
received  perhaps  its  largest  development  in  the  Denver 
and  Rio  Grande  Railway  and  its  branches,  which  wind 


Narrow  Gauge  Railways.  55 

through  the  gorges  of  the  Rocky  Mountains  in 
Colorado.  This  railway  system  was  laid  to  a  gauge  of 
3  feet  between  the  rails,  and  it  extends  over  a  length  of 
1467  miles.  This  arrangement,  however,  has  not  been 
followed  on  more  recent  lines  in  the  United  States.  The 
Peruvian  railways  are  laid  to  the  standard  gauge ;  and 
already  403  miles  of  the  Denver  and  Rio  Grande  lines 
have  been  provided  with  a  third  rail  outside,  to  adapt 
them  to  the  standard  gauge,  thus  widening  the  gauge 
to  4  feet  8^  inches,  just  as  the  Great  Western  Railway 
7-foot  gauge  has  been  narrowed  by  a  third  rail,  with 
the  same  object.  The  promoters  of  the  earlier  narrow 
gauge  lines  in  India,  Australia,  and  elsewhere,  aimed  at 
reducing  the  cost  of  construction  by  diminishing  the 
width  of  the  line,  and  thus  reducing  the  quantity  of  land 
required,  and  the  amount  of  earthwork  in  the  cuttings 
and  embankments,  and  also  by  enabling  sharper  curves 
to  be  adopted,  owing  to  the  smaller  difference  in  curvature 
of  the  two  rails  when  placed  closer  together. 

A  tramway,  having  a  width  of  only  2  feet  between 
the  rails,  was  constructed  as  early  as  1832,  for  the  pur- 
pose of  conveying  slates  from  the  quarries  at  Festiniog 
to  Portmadoc  for  shipment.  The  line  has  a  length  of 
13^  miles,  with  a  difference  in  level  between  the  termini 
of  700  feet ;  and  for  \2\  miles  of  this  distance  the  average 
gradient  descending  to  Portmadoc  is  I  in  92,  the  steepest 
gradient  on  the  line  being  i  in  6o|.  The  line  is  very 
much  curved,  winding  round  the  hills,  and  the  radii  of 
the  curves  are  generally  8  to  7  chains  (176  to  154  yards)  ; 
but  they  descend  in  places  to  6,  5,  4,  and  3  chains, 
and  occasionally  even  to  if  chains  (27^  yards).  Till 
1863,  the  line  was  only  used  as  a  tram  road;  and 
the  little  trucks,  specially  designed  for  carrying  slates, 


56  Working  of  Festiniog  Railway. 

went  loaded  down  the  continuous  incline  by  their 
own  weight,  and  the  empty  trucks  were  hauled  up  the 
ascending  gradients  by  horses.  Locomotives  were  intro- 
duced for  the  first  time  in  1863;  and  in  1865  the  railway 
was  opened  as  a  passenger  line.  The  trains  are  drawn 
up  to  Festiniog  by  locomotives,  and  descend  to  Portmadoc 
by  gravity.  The  traction  up  the  long  incline  is  satis- 
factorily effected  by  duplex  bogie  locomotives,  introduced 
in  1869,  having  two  engines,  united  by  a  tender  common 
to  the  two,  and  hinged  at  the  centre.  These  bogie 
engines,  having  two  pairs  of  coupled  driving-wheels  each, 
called  Fairlie  engines  after  the  name  of  their  designer, 
can  draw  up  a  load  of  150  tons,  and  pass  easily  round 
the  sharp  curves  of  the  line.  This  miniature  railway 
has  worked  very  satisfactorily  since  the  introduction  of 
locomotives  on  it ;  and,  in  addition  to  goods,  it  conveyed 
139,810  passengers  in  1889.  Though  the  gradients  of  the 
Festiniog  Railway  were  considered  steep  at  the  period 
of  its  inauguration  as  a  passenger  line,  steeper  gradients 
are  often  adopted  on  main  lines  in  the  present  day ;  and 
its  ascending  gradient,  12 \  miles  long,  has  been  far  sur- 
passed in  America,  both  in  the  steepness  of  the  maximum 
gradient  and  in  the  length  of  the  incline,  on  lines  of 
the  .ordinary  gauge,  as  described  in  the  last  chapter. 
The  curves  on  this  line  are  unprecedentedly  sharp,  but 
their  employment  enabled  the  cost  of  construction  to 
be  considerably  reduced  in  the  hiily  country  traversed. 

The  powers  of  the  locomotive  have  to  be  considered 
in  settling  the  maximum  gradient  and  sharpest  curve 
that  may  be  adopted.  The  tractive  force  of  a  locomotive 
depends  on  the  adherence  of  the  driving-wheels  to  the 
rails,  which  is  governed  by  the  weight  on  the  driving- 
wheels.  This  adherence  may  be  augmented  by  in- 


Traction  round  Sharp  Curves.  57 

creasing  the  weight  of  the  engine,  and  by  throwing 
as  much  of  this  weight  as  practicable  on  to  the 
driving-wheels.  The  whole  of  the  weight  of  the  loco- 
motive may  be  utilised  by  coupling  all  its  wheels  to- 
gether by  means  of  a  connecting  rod  on  each  side,  and 
thus  converting  them  all  into  driving-wheels  ;  but  this, 
by  rigidly  connecting  all  the  wheels  together,  and,  when 
there  are  three  or  more  pairs  of  wheels,  placing  a  longer 
distance  between  the  front  and  hind  wheels,  which  is 
termed  the  wheel-base,  renders  the  locomotive  less  able 
to  travel  round  curves.  When,  therefore,  steep  gradients 
are  combined  with  sharp  curves,  a  large  rigid  wheel- 
base,  resulting  from  coupling  three  or  more  pairs  of 
wheels  together,  to  increase  the  adherence  on  the  rails, 
is  inadmissible,  especially  where  the  gauge  is  not 
narrow,  for  a  long  rigid  rectangular  frame  cannot 
travel  easily  round  a  sharp  curve.  This  result  is  ob- 
viated in  some  cases  by  only  coupling  two  pairs  of 
large  wheels  close  together,  so  placed  as  to  carry  the 
main  weight  of  the  engine,  and  putting  a  bogie  frame 
on  two  pairs  of  small  wheels  at  the  extreme  front,  so 
as  to  give  stability  and  freedom  of  movement  without 
taking  off  any  large  proportion  of  weight  from  the 
driving-wheels.  The  total  weight,  however,  of  the 
engines  is  utilised  in  the  Fairlie  system,  by  coupling 
the  two  pairs  of  wheels  under  each  engine  ;  whilst  the 
central  pivot,  making  the  two  engines  bogies,  enables 
the  locomotive  to  run  easily  round  very  sharp  curves, 
though  retaining  the  stability  of  a  long  wheel-base. 
Thus  the  wheel-base  of  the  coupled  wheels  of  each 
half  of  the  Fairlie  duplex  locomotive,  introduced  on  the 
Festiniog  Railway,  was  only  5  feet ;  whereas  the  actual 
wheel-base  of  the  combined  locomotive,  or  between  the 


58         Fair  lie  Engines  for  Steep  Railways. 

extreme  wheels  of  the  two  halves,  was  19  feet.  The 
utilisation  of  the  whole  of  the  comparatively  small 
weight  of  1 9^-  tons  was  very  important;  whilst  the 
duplex  system  of  bogie  engines  afforded  great  stability, 
and  yet  allowed  the  locomotive  to  travel  round  experi- 
mental curves  of  only  50  feet  radius.  The  same  type 
of  locomotive  has  been  employed  in  Sweden ;  and  a 
Fairlie  locomotive  was  constructed  for  the  Central  Pacific 
Railway,  at  the  time  of  its  opening,  to  draw  trains  up  the 
long  and  steep  inclines  of  the  Sierra  Nevada.  As,  how- 
ever, the  gradients  are  steeper  and  much  longer  on  this 
line  than  on  the  Festiniog  line,  whilst  the  curves  are 
much  easier,  each  half  of  the  duplex  locomotive  was 
provided  with  three  pairs  of  wheels  coupled,  3-J-  feet  in 
diameter;  and  the  total  weight  of  the  locomotive  was 
54  tons.  As  already  mentioned  in  the  last  chapter,  Fairlie 
engines  are  employed  on  the  steep  portion  of  the  line 
from  Vera  Cruz  to  Mexico,  where  the  gradients  reach 
I  in  25,  and  the  curves  5  chains  (no  yards)  radius, 
for  which  they  are  specially  well  suited ;  and  the 
same  type  of  locomotive  is  used  on  the  Iquique  Rail- 
way in  Southern  Peru,  which  rises  to  3067  feet  above 
sea  level  in  the  first  19  miles,  on  its  way  to  the  nitrate 
of  soda  mines,  with  a  maximum  gradient  of  I  in 
25,  and  curves  of  from  15  to  5  chains  (330  to  no 
yards)  radius. 

Several  pioneer  lines  in  Canada,  the  Cape  Colony, 
Australia,  New  Zealand,  Tasmania,  and  Japan  have 
been  laid  to  a  3^-foot  gauge,  and  some  branch  lines  in 
India,  Brazil,  and  the  Argentine  Republic  to  a  metre 
(3^  feet)  gauge,  with  the  object  of  reducing  the  cost  of 
construction.  The  general  opinion,  however,  amongst 
engineers  is  that,  in  most  cases,  the  saving  in  expense 


Gauges  for  Mountain  Railways.  59 

of  construction  is  more  than  counterbalanced  by  the  in- 
conveniences and  cost  of  a  break  of  gauge,  involving  the 
transhipment  of  passengers  and  goods,  and  two  classes 
of  rolling  stock ;  and  in  the  United  States  uniformity  of 
gauge  is  being  gradually  attained.  Some  narrow  gauge 
railways,  indeed,  in  Mexico  have  been  constructed  so  as 
to  be  easily  converted  into  lines  of  ordinary  gauge  as  soon 
as  the  traffic  shall  have  adequately  developed.  Moreover, 
the  superiority  of  the  narrow  gauge  over  the  standard 
gauge,  in  suitability  for  sharp  curves,  has  been  to  a  great 
extent  eliminated  by  the  adoption  of  the  bogie  system, 
which,  by  introducing  a  pair  of  pivoted  bogie  trucks 
under  each  carriage,  enables  the  whole  train  to  run 
without  danger  or  jar  round  most  curves.  Although  no 
engineer  has  ventured  to  introduce,  on  railways  of  the 
ordinary  4  feet  8^  inches  gauge,  as  sharp  curves  as  those 
successfully  employed  in  the  Festiniog  line,  with  its  2-foot 
gauge,  the  most  formidable  obstacles  have  been  sur- 
mounted on  the  Oroya  line  with  curves  of  5  chains 
(no  yards)  radius.  The  admissibility  of  curves  of 
5  chains  (no  yards)  radius  on  lines  of  the  standard 
gauge  has  been  amply  proved  by  their  insertion  in  places 
on  the  Ceylon  Government  railways,  of  which  the  gauge 
is  5^  feet,  like  the  main  lines  of  India.  Accordingly, 
though  narrow  gauges  have  been  advantageously  used 
for  some  mountain  railways  and  pioneer  lines,  with  the 
object  of  diminishing  the  cost  of  construction,  they  do 
not  appear  likely  to  be  extensively  adopted  in  the  future, 
except  in  places  removed  from  contact  with  railways  of 
the  ordinary  gauge,  or  under  special  conditions. 

Fell  Railways. — The  steepest  gradient  hitherto  con- 
sidered  surmountable   by  ordinary  locomotives,  drawing 


6o  Fell  Railway  on  Mont  Cents. 

a  regular  train,  is  I  in  25,  which  has  only  been  em- 
ployed in  the  exceptional  instances  of  the  Mexican 
and  Peruvian  railways.  When,  however,  the  slow 
progress  of  the  Mont  Cenis  tunnel,  by  hand  labour,  for 
the  first  three  or  four  years,  seemed  likely  to  post- 
pone for  several  years  the  opening  of  the  Mont  Cenis 
Railway,  Mr  Fell  proposed  to  complete  the  gap  in  the 
railway  communication,  of  48  miles,  between  St  Michel 
and  Susa,  by  constructing  a  line  suitable  for  a  special 
form  of  locomotive  along  the  Mont  Cenis  road.  The 
system  consisted  of  an  ordinary  double-headed  rail  laid 
horizontally  between  the  two  rails,  in  the  centre  of  the 
line  of  way,  and  at  a  higher  level,  gripped  by  horizontal 
wheels  on  each  side,  introduced  underneath  the  loco- 
motive. By  gripping  this  central  rail,  the  locomotive 
obtained  additional  adherence  for  ascending  the  steep 
gradients  of  the  highroad  over  the  Mont  Cenis  Pass, 
and  brake  power  for  the  descent,  and  also  security 
against  running  off  the  line  in  going  round  the  sharp 
curves  of  the  road.  The  railway  was  commenced  in  1866, 
and  opened  for  traffic  in  1868  ;  it  followed  the  outer  side 
of  the  Mont  Cenis  road,  except  where  diversions  became 
necessary  to  secure  a  more  uniform  gradient,  or  to  avoid 
villages.  The  railway  was  laid  to  a  gauge  of  3  feet 
7f  inches,  with  a  maximum  gradient  of  I  in  12,  and  curves 
having  a  minimum  radius  of  2  chains  (44  yards).  The 
rise  from  St  Michel,  on  the  French  side,  to  the  summit  is 
about  4600  feet ;  the  summit  of  the  pass  is  6772  feet  above 
sea  level ;  and  the  descent  to  Susa,  on  the  Italian  side,  is 
about  5300  feet.  The  slope  on  the  Italian  side  is  con- 
siderably steeper  than  on  the  French  side.  The  central 
rail  was  laid  on  all  gradients  steeper  than  I  in  25,  and 
was  raised  7|  inches  above  the  surface  of  the  ordinary 


Central  Rail  Mountain  Railways.  6 1 

rails.  Though  following  the  steep  inclines  and  sharp 
turns  of  an  Alpine  mountain  road,  the  trains  ran  with 
remarkable  ease  and  safety.  The  trains  performed  the 
journey  in  six  hours  shorter  time  than  the  diligences, 
which  enabled  an  accelerated  mail  service  to  India,  via 
Brindisi,  to  be  started.  Trains  weighing  36  tons  were 
drawn  up  the  line ;  and  28,000  passengers  travelled  by  it 
in  the  course  of  a  year.  Difficulties  were  naturally  ex- 
perienced in  keeping  the  line  free  from  snow,  though  nine 
miles  of  covered  way  were  constructed  where  the  line  was 
most  exposed  to  snow  drifts,  or  liable  to  avalanches ;  but 
the  trains  were  run  with  very  few  interruptions,  till  the 
line  had  to  be  closed  on  the  opening  of  the  tunnel  line  in 
September  1871. 

A  more  permanent  line,  on  the  same  system,  has  been 
constructed  on  an  extension  of  the  Cantagallo  Rail- 
way in  Brazil,  which  rises  3000  feet  in  about  10  miles, 
for  crossing  the  Serra,  with  gradients  of  I  in  20  to 
I  in  12;  and  it  winds  round  the  projecting  spurs,  with 
curves  of  from  2  to  5  chains  (44  to  1 10  yards)  radius.  After 
surmounting  the  ridge,  it  descends  with  easier  gradients  to 
Nova  Friburgo.  The  gauge  of  this  line  is  3  feet  7f  inches, 
like  the  temporary  Mont  Cenis  mountain  line.  Fell  loco- 
motives carried  on  the  traffic  up  the  incline  satisfactorily 
for  some  years,  since  about  1872 ;  but,  in  the  last  two  or 
three  years,  Baldwin  locomotives,  from  Philadelphia,  have 
been  introduced,  which,  weighing  40  tons,  and  having 
eight  wheels  coupled,  can  draw  a  load  of  38  tons  up  the 
incline  of  I  in  12  at  the  rate  of  8  miles  an  hour.  The 
Fell  system  is  undoubtedly  better  than  the  ordinary  loco- 
motive for  drawing  trains  up  steep  inclines  with  sharp 
curves  ;  but  when  the  steep  incline  forms  only  a  small 
part  of  the  whole  line,  the  employment  of  ordinary  heavy 


62  Fell  System  in  New  Zealand. 

locomotives  capable  of  making  the  ascent  enables  other 
types  of  engines  to  be  dispensed  with.  The  Fairlie 
locomotive,  however,  has  proved  superior  to  the  Baldwin 
locomotive  for  drawing  trains  up  the  long  gradients  ot 
I  in  25  of  the  Mexican  Railway. 

Fell  locomotives  have  been  running  for  over  ten  years 
on  the  Wellington  and  Featherstone  Railway  in  New 
Zealand,  where  there  is  a  gradient  of  i  in  1 5  for  a  length 
of  about  2\  miles.  The  Rimutaka  range  stretches  across 
the  route  of  the  railway,  and  the  lowest  point  for  crossing 
it  is  over  the  Rochfort  saddle,  1448  feet  above  sea  level. 
The  ascent  of  the  range  from  the  Wellington  side  has 
been  effected  with  a  maximum  gradient  of  I  in  35  ;  but 
the  descent,  on  the  opposite  slope,  is  so  steep  that  a 
continuous  gradient,  of  I  in  15,  was  resorted  to  in  order 
to  keep  the  works  within  reasonable  limits  ;  and  the 
central  rail  system  was  adopted  for  conducting  the  traffic 
over  it,  with  one,  two,  or  three  engines,  according  to 
the  load.  A  tunnel  of  less  than  half-a-mile,  piercing  the 
highest  part  of  the  ridge,  reduced  the  summit  level  of  the 
railway  to  1141  feet  above  sea  level,  307  feet  below  the  top 
of  the  ridge.  The  gauge  of  the  line  is  3^-  feet,  and  the 
sharpest  curves  have  a  radius  of  5  chains  (no  yards). 

The  Rigi  Railways. — It  has  been  seen  that  the 
central  rail  system  has  enabled  gradients  of  I  in  12  to 
be  surmounted  without  difficulty,  by  special  locomotives, 
even  when  combined  with  sharp  curves.  When,  how- 
ever, mountain  sides  had  to  be  scaled,  a  different  system 
was  needed.  The  first  idea  of  carrying  tourists  up  a 
mountain  by  rail,  instead  of  by  road,  appears  to  have 
been  conceived  by  Mr  S.  Marsh,  in  the  United  States,  in 
1857,  who  proposed  to  make  a  rack  railway  for  conveying 


Rack  Railway  up  the  Rigi.  63 

persons  to  the  top  of  Mount  Washington,  the  highest  of  the 
White  Mountains,  in  New  Hampshire.  Though  treated 
at  first  as  the  dream  of  a  madman,  the  work  was  eventu- 
ally carried  out  between  1867  and  1869.  The  gradients 
were  limited  to  a  maximum  of  I  in  3,  and  the  curves  to 
a  minimum  radius  of  about  7^  chains  (165  yards);  and 
timber  was  largely  employed  in  carrying  the  line  across 
hollows.  A  similar  system,  on  an  improved  plan,  has 
been  adopted  for  the  construction  of  railways  to  the  top 
of  the  Rigi.  This  mountain  is  well  known  to  all  travellers 
in  Switzerland  visiting  Lucerne  from  the  beautiful  view 
obtained  from  its  summit,  which  is  5906  feet  above  sea 
level.  The  railway  was  commenced  from  Vitznau,  on  the 
Lake  of  Lucerne,  in  1869;  it  was  opened  up  to  about  a 
mile  from  the  summit  in  1871,  and  completed  in  1873.  It 
has  a  total  length  of  about  4^  miles  ;  and  the  rise  from  the 
Lake  of  Lucerne  is  4472  feet.  The  engine  and  carriage 
run  on  rails  laid  to  the  ordinary  gauge ;  but,  unlike  the 
systems  previously  described,  the  tractive  force  is  not 
obtained  by  adherence  to  the  rails,  or  by  gripping  a 
central  rail,  but  by  means  of  a  cog-wheel  working 
in  a  central  rack  laid  on  the  incline  between  the  rails.  (See 
illustration.)  In  ascending,  the  cog-wheel,  in  revolving, 
mounts  the  sort  of  inclined  ladder  formed  by  the  rack, 
and  thus  draws  the  engine  and  vehicle  up  with  it.  The 
line  has  a  gradient  of  I  in  4  for  about  one-third  of  its 
length  ;  and  the  gradient  of  the  remaining  portion  is  never 
less  than  I  in  6,  except  where  nearly  level  pieces  are  intro- 
duced at  the  stations.  The  curves  employed  have  a  radius 
of  8-|  chains  (187  yards).  The  rails  and  rack  are  laid  on 
a  strong  framing  of  cross  sleepers,  fastened  to  longitudinal 
timbers,  so  as  to  insure  the  maintenance  of  the  position 
of  the  rack  ;  and  the  framing  is  prevented  from  sliding 


64  Extension  of  Rigi  Railways. 

down  hill  by  being  secured  at  intervals  to  masonry 
foundations  built  into  the  solid  rock.  The  engine  and 
carriage  are  controlled,  in  descending  the  steep  incline,  by 
a  powerful  brake  acting  upon  the  axle  of  the  driving  cog- 
wheel, which,  when  stopped  from  revolving,  keeps  a  cog 
engaged  in  the  rack,  and  thus  arrests  the  descent ;  another 
cog-wheel,  also,  is  placed  on  the  front  axle  of  the  engine, 
which  can  be  prevented  from  revolving  in  the  same 
manner  as  the  driving  axle;  and  a  sort  of  air  brake  can 
also  be  supplied  to  the  piston.  Accordingly,  the  carriage, 
containing  accommodation  for  fifty-four  persons,  can  be 
pushed  up,  or  led  down  the  mountain  sides  in  perfect 
safety,  at  an  average  rate  of  about  4f  miles  per  hour. 

Another  similar  line  has  since  been  constructed,  start- 
ing from  Arth,  on  the  Lake  of  Zug,  and  rising  up  the 
opposite  side  of  the  mountain.  The  maximum  gradient 
on  the  Arth  line  is  I  in  5.  There  are  two  carriages  in 
each  train  on  this  line,  capable  of  holding  forty  persons 
each.  The  view  in  ascending  this  slope  is  not  so  fine  as 
on  the  Vitznau  line,  but  the  grand  panorama  bursts  with 
more  effect  on  the  traveller  on  approaching  the  summit. 

A  third  railway  has  also  been  constructed  on  the  Rigi, 
worked  in  the  ordinary  manner,  by  locomotives  suited  for 
steep  gradients  ;  it  traverses  the  upper  part  of  the  moun- 
tain from  the  Kaltbad  Hotel,  which  is  at  an  elevation  of 
4700  feet,  and  a  little  over  a  mile  from  the  Rigi  Kulm,  or 
principal  summit,  to  the  Rigi  Scheidegg,  another  summit, 
5407  feet  above  sea  level.  The  line  winds  about  a  good 
deal  in  contouring  the  slopes,  and  has  a  length  of  4^  miles, 
which  is  traversed  in  25  minutes.  This  railway  is  at  a 
higher  level  than  the  summit  level  of  the  Brenner,  the 
highest  of  the  main  Alpine  railways,  and  the  Rigi  Kulm  is 
1400  feet  higher  than  the  Brenner  Railway  summit ;  but 


Rack  Railway  lip  Pilatus.  65 

this  does  not  signify  materially  in  respect  of  obstruction 
by  snow,  as  these  railways  only  run  during  the  summer 
months  of  the  year. 

The  Pilatus  Railway. — -A  rack  railway,  with  steeper 
slopes,  and  attaining  a  higher  level  than  the  Rigi  Railway, 
for  the  purpose  of  ascending  to  the  summit  of  Mont 
Pilatus,  was  opened  in  1889.  The  railway  starts  from 
Alpnach,  on  the  Lake  of  Lucerne,  and  ascends  5363  feet 
to  the  summit,  68 1 2  feet  above  sea  level.  The  total  length 
of  the  line  in  which  this  ascent  is  accomplished  is  only 
2f  miles,  half  of  which  is  straight,  and  half  has  curves  of 
4  to  5  chains  (88  to  1 10  yards)  in  radius.  The  inclines  of 
the  railway  are  consequently  very  steep,  the  rise  averaging 
rather  less  than  I  in  3,  which  is  equivalent  to  a  rise  of  I  foot 
for  each  3  feet  traversed,  or  nearly  the  slope  of  a  staircase; 
and  the  steepest  portions  have  a  rise  of  I  in  2.  The  road, 
therefore,  had  to  be  made  very  solid,  to  prevent  a  chance 
of  its  sliding  down  gradually,  and  the  engine  and  carriage 
as  light  as  possible  on  so  steep  an  incline.  The  line  is 
laid  on  iron  sleepers,  bolted  to  solid  longitudinal  masonry 
walls  founded  in  the  solid  rock.  The  two  ordinary  iron 
rails  on  which  the  carriage  runs  are  laid  to  a  gauge  of 
2  feet  7-J  inches;  and  the  rack  rail,  with  teeth  on  each 
side,  composed  of  steel,  is  placed  in  the  centre  between 
the  rails.  Masonry  bridges  carry  the  line  over  streams  and 
gorges,  and  the  line  traverses  seven  short  tunnels.  The 
engine  and  carriage  have  been  placed  on  the  same  frame, 
for  the  sake  of  lightness,  and  run  on  two  pairs  of  wheels ; 
whilst  two  pairs  of  horizontal  cog-wheels  work  on  each  side 
of  the  rack.  The  vehicle  has  necessarily  to  be  provided  with 
very  powerful  brakes,  to  ensure  its  not  breaking  away 
down  the  steep  incline.  There  are  two  hand  brakes,  one  of 


66  Rack  Railways  up  Mountains. 

which  alone  could  stop  the  vehicle  in  its  descent ;  there  is 
also  an  atmospheric  brake,  acting  on  the  piston,  as  on  the 
Rigi  Railway;  and  there  is  also  an  automatic  brake,  in  re- 
serve, which  comes  into  action  directly  the  downward  speed 
exceeds  about  3  miles  an  hour,  so  that  the  safety  of  the 
vehicle  is  secured  as  far  as  possible.  Seats  are  provided 
for  thirty-two  persons,  which  are  jointed  so  as  to  adjust 
themselves  to  changes  of  incline.  The  line  was  carried 
out  in  sections,  commencing  at  the  base,  whereby  the 
security  of  the  line  could  be  tested,  and  materials  conveyed 
by  the  completed  line  for  the  construction  of  the  next 
length  higher  up.  The  vehicle  is  provided  with  two 
clips,  encircling  the  head  of  each  rail,  so  as  to  prevent  its 
being  blown  off  the  road  by  the  vehement  storms  which 
occasionally  burst  upon  the  mountain.  The  surmounting 
of  inclines  of  I  in  2  by  a  self-propelling  carriage  is  a  very 
remarkable  feat,  and  has  not  been  surpassed  elsewhere, 
though  the  load  carried  is  very  small  compared  to  ordi- 
nary trains. 

A  similar  rack  railway  has  recently  been  constructed 
from  Capo  di  Lago,  on  the  St  Gothard  Railway,  at  the 
Italian  end  of  Lake  Lugano,  to  the  summit  of  Monte 
Generoso,  5561  feet  above  sea  level.  The  rise  of  4620 
feet  is  accomplished  by  a  length  of  line  of  about  5  miles, 
with  gradients,  in  this  case,  of  only  I  in  4^  to  I  in  5. 
The  sharpest  curves  have  a  radius  of  3  chains  (66  yards), 
and  the  gauge  of  the  railway  is  2  feet  7-*-  inches.  The 
ascent  is  accomplished  in  about  an  hour ;  and  magnifi- 
cent views  of  the  Alps,  the  Italian  lakes,  and  the  plains 
of  Lombardy  are  obtained  from  the  summit. 

A  bt  Rack  System  for  Mountain  Railways. — The  rack 
system  has  not  been  confined  to  tourist  lines,  but  has 


Abt  Rack  Mountain  Railways.  67 

also  been  employed  for  ascending  specially  steep  inclines 
on  ordinary  railways,  or  for  affording  railway  accommo- 
dation to  towns  occupying  elevated  positions.     Thus  the 
Abt  system,  combining  traction  by  adhesion  with  traction 
by   a  rack  and  pinion,   has  been  employed  for  working 
the  traffic  on  the   Hartz   Mountain   Railway,  where  the 
steepest  gradients  are  I  in  16;  and  the  rack  system  has 
been  adopted  for  taking  trains  up  a  gradient  of  I  in  12, 
about  a  mile  and  a  half  in  length,  on  the  Puerto  Cabello  and 
Valencia  Railway  of  Venezuela.     The  railway,  also,  from 
Visp  to  Zermatt,  about  22^-  miles  long,  having  a  3^  feet 
gauge,gradients  of  I  in  8^, and  curves  of  5  chains  ( 1 10  yards), 
and  the  railway  from  Eisenerz  to  Vordenberg  in  Styria, 
I2|-  miles   long,  of  ordinary  gauge,  with  gradients  of  I 
in  14,  and  curves  of  9  chains  (198  yards)  radius,  are  con- 
structed with  the  addition  of  a  rack  to  aid  the   tractive 
force  of  adhesion  at  the  steep  inclines.     The  rack  prin- 
ciple  is   specially    advantageous    for    enabling   trains    to 
ascend  short  steep  inclines,  situated  at  various  places  on 
a  railway,  which  could  not  be  surmounted  with  consider- 
able loads  by  adhesion   alone  ;   and  such  inclines,  being 
scattered  about  the  railway,  would  not  be  well  adapted 
for  the  employment  of  the  older  system  of  rope  traction 
for  steep  inclines,  by  means  of  a  stationary  engine,  so 
much  used   in    mines,  and  adopted  with  advantage  for 
the  haulage   of  tramcars   up   steep   ascents,   notably   at 
San  Francisco.     There  would  be  the  same  advantage  in 
the   use   of    the    central    rail    system,   except    that   the 
machinery  of  the   locomotive   for   gripping   the    central 
rail    is    more    complicated    than    the    arrangements    for 
working  in  a  rack;   and   locomotives  of  this  type  have 
not  hitherto  been  made  equally  serviceable  for  ordinary 
work. 


68  Transandine  Railway  in  Progress. 

An  interesting  example  of  the  application  of  the  rack 
system  to  occasional  steep  inclines  is  furnished  by  the 
Transandine  Railway,  in  course  of  construction,  for  con- 
necting Buenos  Ayres  on  the  Atlantic  with  Valparaiso  on 
the  Pacific,  which  has  to  traverse  the  Chilian  Andes  at  an 
elevation  of  10,466  feet  above  sea  level,  in  a  summit  tunnel 
3-f  miles  long.  The  lowest  ridge  of  the  Andes  in  these 
parts  rises  12,467  feet  above  the  sea  ;  and  though  2000  feet 
of  this  rise  are  saved  by  the  summit  tunnel,  it  has  been 
found  necessary,  for  saving  expense  and  avoiding  ava- 
lanches, to  introduce  several  inclines  of  I  in  12^  on  the 
mountain  section  of  the  railway  between  Mendoza  in  the 
Argentine  Republic  and  Santa  Rosa  in  Chili,  a  distance 
of  149  miles.  Abt  locomotives  will  work  in  a  rack  on 
these  steep  inclines  which  will  extend  over  17  miles  of 
the  line,  there  being  one  continuous  steep  incline  10  miles 
long  on  the  Chilian  slope,  and  the  other  7  miles  of  in- 
clines distributed.  The  length  of  the  completed  railway 
from  Buenos  Ayres  to  Mendoza  is  648  miles,  laid  to  a 
gauge  of  5^  feet ;  and  of  the  railway  from  Valparaiso  to 
Santa  Rosa,  on  the  Pacific  side,  53  miles,  having  a  gauge 
of  4  feet  S-|-  inches.  The  mountain  section  of  the  railway 
is  to  have  a  gauge  of  3^  feet;  the  first  84  miles  from 
Mendoza  has  gradients  not  exceeding  I  in  40,  and  only 
the  western  65  miles  will  require  Abt  locomotives.  The 
line,  accordingly,  from  ocean  to  ocean,  will  be  850  miles 
long,  very  much  shorter  than  the  Pacific  lines  of  North 
America,  but  it  will  have  three  different  gauges. 

The  problem  of  cheaply  and  efficiently  working  ordi- 
nary railway  traffic  up  steep  inclines  is  of  great  importance 
for  the  future  development  of  railways.  If  an  economical 
method  of  hauling  trains  up  occasional  steep  inclines  can 
be  attained  by  the  Abt  system,  or  any  other,  more  especi- 


Locomotive  for  Flat  and  Steep  Gradients.      69 

ally  with  the  same  engine  employed  along  the  flatter 
parts  of  the  line,  steep  inclines  could  be  introduced  with- 
out hesitation  wherever  abrupt  changes  of  level  in  a 
country  render  them  expedient,  and  a  great  reduction 
in  the  cost  of  construction  of  a  railway  through  moun- 
tainous districts  wo*uld  be  thereby  secured. 


CHAPTER    IV, 

PIERCING   THE  ALPS. 

THE  construction  of  tunnels  is  generally  a  slow  and 
somewhat  uncertain  kind  of  work.  The  exact  nature 
of  the  material  to  be  traversed  at  some  distance  from 
the  surface  is  imperfectly  known  ;  faults  may  be  encoun- 
tered, slips  may  occur,  and  springs  may  burst  forth. 
One  of  the  earliest  tunnels  on  record  is  said  to  have  been 
made  in  1608,  for  draining  the  plateau  on  which  the  City 
of  Mexico  stands.  It  passed  under  the  ridge  of  Nochis- 
tengo,  for  a  distance  of  6  miles,  through  a  peculiar  kind  of 
earthy  stratum  called  tepetate  ;  and  it  is  stated  to  have 
been  executed  in  the  remarkably  short  period  of  eleven 
months.  The  conditions  must,  however,  have  been  ex- 
ceptionally favourable,  if  the  period  given  is  correct ;  but 
the  tunnel  was  destroyed  during  a  flood,  and  an  open 
cutting,  with  a  maximum  depth  of  200  feet,  was  substi- 
tuted for  it,  after  great  labour  and  the  loss  of  many  lives. 
The  first  tunnel  made  in  England  was  the  Harecastle 
Tunnel,  for  the  Trent  and  Mersey  Canal ;  and  eleven  years, 
1766  to  1777,  were  employed  in  its  construction,  though 
its  length  is  only  i  mile  5  furlongs.  On  the  introduction, 
however,  of  railways,  tunnelling  became  more  common 
and  more  expeditious  ;  and  several  railway  tunnels  have 
been  constructed  in  England  of  more  than  a  mile  in 
length.  Amongst  some  of  the  longest  of  these  are  the 
Box  Tunnel,  on  the  Great  Western,  near  Bath,  I  mile 


Construction  of  Alpine  Tunnels.  71 

6f  furlongs  long  ;  the  Sevenoaks  Tunnel,  on  the  South- 
Eastern  main  line,  a  little  over  2  miles  long ;  the  Bram- 
hope  Tunnel,  on  the  North-Eastern  Railway,  near  Leeds, 
2  miles  i  furlong  in  length ;  the  Woodhead  Tunnel,  be- 
tween Manchester  and  Sheffield,  3  miles  long  ;  and  the 
Standege  Tunnel,  on  the  London  and  North- Western 
Railway,  between  Manchester  and  Huddersfield,  a  little 
more  than  3  miles  long.  All  these  tunnels,  however, 
besides  being  excavated  from  each  extremity,  were  also 
approached  by  vertical  shafts  sunk  from  the  surface,  on 
the  line  of  the  tunnel,  down  to  the  level  adopted  for  the 
railway  ;  and  thus  it  was  possible  to  attack  two  more 
faces  of  the  tunnel  from  each  shaft,  and  thereby  greatly 
expedite  the  work.  On  the  contrary,  when  the  construc- 
tion of  the  Alpine  tunnels  had  to  be  undertaken,  for  pierc- 
ing the  steep  ridges  intervening  between  the  summit 
levels  of  the  Alpine  railways,  no  shafts  were  practicable 
on  the  high  ridges.  The  tunnels  could,  therefore,  be  only 
driven  from  each  end ;  and  in  every  case  the  material  to 
be  excavated  for  the  tunnel  was  composed  of  the  hardest 
primitive  rocks,  which  had  resisted  for  ages  the  disintegrat- 
ing influences  of  snow,  ice,  and  atmospheric  changes. 

In  designing  railways  through  mountainous  regions, 
it  is  expedient  if  possible,  with  a  main  line  subject  to 
competition,  to  restrict  the  open  portion  of  the  railway 
to  an  altitude  where  it  is  not  liable  to  be  frequently 
blocked  by  snow  drifts.  This  has  not  been  practicable 
on  the  North  American  lines  leading  to  the  Pacific 
Ocean,  owing  to  the  great  width  of  the  ranges  traversed  ; 
and  the  great  cost  of  long  tunnels  would  have  prohibited 
their  adoption  on  the  Peruvian  railways.  On  the  Alps, 
however,  though  the  ridges  to  be  traversed  were  not  quite 
insurmountable,  as  proved  by  the  temporary  working  of 


72          Considerations  affecting  Alpine  Lines. 

the  Fell  system  of  railway  over  the  Mont  Cenis,  the 
heights  to  be  attained  would  have  approached  the  line  of 
perpetual  snow,  and  therefore  it  would  have  been  very 
difficult  to  keep  the  railway  open  in  the  winter.  The 
increasing  steepness,  also,  of  the  upper  parts  of  the  valleys, 
would  have  rendered  a  very  circuitous  line  and  steeper 
gradients  indispensable,  together  with  increasingly  heavy 
works.  The  ridges,  also,  separating  the  valleys  on  each 
side,  were  in  places  sufficiently  reduced  in  width  to  suggest 
the  possibility  of  a  tunnel,  though  exceeding  in  magnitude 
any  previous  works  of  the  kind.  Moreover,  even  a  large 
outlay  on  a  tunnel  might  not  be  unwisely  undertaken  in 
providing  a  railway  with  fair  gradients,  of  sufficiently 
moderate  altitude  to  be  kept  open  generally  in  winter 
without  great  difficulty,  and  thus  securing  the  main  traffic 
between  Northern  Europe  and  Italy  and  the  East  These 
are  the  principles  which  were  kept  in  view  in  laying  out 
the  Mont  Cenis  and  St  Gothard  railways  ;  and  it  is  certain 
that  if  one  of  these  had  been  made  a  circuitous,  steep, 
open  line,  and  the  other  made  in  its  existing  form,  the  more 
direct  and  easier  tunnel  line,  less  exposed  to  delays  in 
winter,  would  have  secured  almost  the  whole  of  the  through 
traffic.  The  open  portions,  indeed,  of  the  Mont  Cenis  and 
St  Gothard  railways,  in  reaching  altitudes  on  the  colder 
northern  slopes  of  3793,  and  3638  feet  respectively  above 
sea  level,  have  approximately  attained  the  limit  of  toler- 
able freedom  from  interruption  of  traffic  amongst  those 
lofty,  precipitous,  glacial  regions,  for  the  lines  have  occa- 
sionally been  blocked  by  snow  drifts.  One  of  the  advan- 
tages of  the  proposed  Simplon  Railway  is  that  its  open 
portion,  on  the  northern  slope,  would  only  attain  an 
altitude  of  2690  feet  above  sea  level,  and  would  therefore 
be  more  secure  from  interruption  by  snow  than  the  Mont 


Heat  at  Great  Depths  Underground.  73 

Cenis  or  St  Gothard  lines ;  whilst  this  lower  altitude  could 
be  reached  by  easier  gradients. 

Another  point  of  considerable  importance,  in  selecting 
the  route  of  these  Alpine  tunnels,  is  the  internal  heat  that 
is  encountered  in  rocks  lying  at  a  great  depth  below  the 
surface ;  for  this  heat  increases  in  proportion  to  the  depth 
of  the  strata  below  the  surface.  Accordingly,  it  is  pro- 
bable that  the  heat  experienced  in  working  at  a  depth 
below  the  surface  exceeding  6000  or  7000  feet,  to- 
gether with  the  confined  space  in  a  tunnel,  the  fumes  from 
blasting,  and  the  difficulty  of  affording  adequate  ventila- 
tion at  a  long  distance  from  the  outlet,  would  render  it 
hazardous  to  attempt  driving  a  tunnel  at  depths  much 
greater  than  the  limits  named. 

The  Mont  Cenis  Tunnel. — The  site  between  Fourneaux 
and  Bardonneche,  under  the  Col  de  Frejus,  was  indicated, 
as  early  as  1840,  as  the  most  suitable  direction  for  an 
Alpine  tunnel,  to  afford  railway  communication  between 
France  and  Italy.  It  was  not,  however,  till  1852  that  the 
proposal  was  seriously  entertained  ;  and  the  works  were 
only  actually  commenced  in  1857.  The  driving  of  a 
tunnel  more  than  seven  and  a  half  miles  long,  without  in- 
termediate shafts,  through  the  hardest  rocks,  composed 
mainly  of  calcareous  and  carboniferous  schists,  with  com- 
paratively small  thicknesses  of  quartz  and  of  limestone, 
was  in  1857  a  work  without  a  parallel  in  the  annals  of 
engineering.  A  somewhat  similar  undertaking,  but  of  less 
magnitude,  had  indeed  been  previously  commenced  in  the 
United  States  ;  for  the  Hoosac  Tunnel,  under  the  Green 
Mountains,  on  the  line  between  Troy  and  Greenfield,  was 
begun  in  1854,  to  afford  Massachusetts  railway  communi- 
cation with  the  west.  The  Hoosac  Tunnel,  however,  the 


74       Method  of  Constructing  Alpine  Tunnels. 

longest  tunnel  in  the  United  States,  traversing  mica  schist 
and  micaeous  granitic  gneiss,  has  a  length  of  only  4f  miles  ; 
it  progressed  very  slowly,  from  one  extremity  only,  till  1 864, 
and  was  not  finally  completed  till  1876.  Moreover,  this 
tunnel  was  constructed  by  the  aid  of  a  central  shaft,  1028 
feet  in  depth,  and  two  or  three  minor  ones,  so  that,  except 
with  regard  to  difficulties  about  funds,  it  was  executed  under 
more  favourable  conditions  than  the  Mont  Cenis  Tunnel. 

The  three  long  Alpine  tunnels,  the  Mont  Cenis,  the  St 
Gothard,  and  the  Arlberg,  have  all  been  driven  in  a  per; 
fectly  straight  line  between  their  two  extremities,  and  have 
been  carried  out  simultaneously  from  the  two  ends  to- 
wards the  centre,  with  rising  gradients  inwards  so  as  to 
provide  for  drainage.  A  very  careful  survey  had  to  be 
made  of  the  district,  to  fix  the  precise  line  of  the  tunnel, 
which  was  marked  out  along  the  surface  ;  and  observa- 
tories were  placed  on  prolongations  of  the  straight  line, 
across  the  further  side  of  the  valleys,  opposite  each  end  of 
the  tunnel,  by  means  of  which  the  exact  direction  was 
constantly  checked  as  the  work  progressed.  The  mainten- 
ance of  the  correct  line  on  each  side  was  most  important, 
as  an  error  in  direction  would  have  prevented  the  meeting 
of  the  two  headings  of  the  tunnel  near  the  centre,  which 
would  have  involved  great  cost  and  delay  in  rectifying. 

The  Mont  Cenis  Tunnel  was  commenced  at  both  ends 
towards  the  close  of  1857  ;  and  the  work  of  boring  the 
holes  for  the  blasting  charges  was  carried  on  by  hand  till 
the  end  of  1860  at  the  southern  heading,  and  till  1862  at 
the  northern  heading,  when  perforating  machinery  was 
introduced.1  The  progress  with  hand- boring  was  neces- 

1  A  "heading"  is  the  advanced  gallery  or  passage  which  is  formed  a  little 
in  advance  of  the  main  excavation  of  a  tunnel,  and  from  which  the  tunnel 
is  subsequently  enlarged  to  the  full  size  as  the  work  proceeds. 


Progress  of  the  Mont  Cents  TunneL  75 

sarily  slow,  so  that  the  advanced  heading  had  only  reached 
a  distance  of  793  yards  from  the  Bardonneche  end  in  1860, 
and  1007  yards  from  the  Fourneaux  end  in  1862,  making 
an  average  yearly  progress  of  about  440  yards.  At  this 
rate,  the  tunnel  would  have  required  about  thirty  years  for 
its  construction  ;  but  the  introduction  of  rock  drills,  worked 
by  compressed  air,  supplied  by  air  compressors  moved  by 
water  power  at  each  end  of  the  tunnel,  accelerated  the 
progress  considerably.  The  rate  of  advance  differed  greatly 
according  to  the  strata  pierced,  the  least  advance  during  a 
month  with  the  machines  having  averaged  at  one  of  the 
faces  only  1.17  feet  per  day  when  traversing  quartz,  and 
the  greatest  advance,  12.9  feet  per  day  in  carbonaceous 
schist.  The  average  yearly  advance  after  the  introduction 
of  the  machines  was  1286  yards,  so  that  the  average  rate 
of  progress  was  nearly  trebled  by  the  machines,  and  more 
than  trebled  during  the  last  seven  years  of  the  works  ;  the 
average  daily  progress  throughout  was  2.57  yards.  The 
tunnel  was  enlarged  by  stages  as  the  work  proceeded,  from 
the  advanced  gallery  or  heading  at  the  base,  9^  feet  wide 
and  8i  feet  high,  to  the  completed  tunnel,  arched  at  the 
top  with  brickwork  and  having  masonry  side  walls,  and  of 
sufficient  size  for  an  up  and  down  line.  The  advanced 
heading  was  driven  by  boring  about  eighty  holes  in  the 
face  of  the  rock,  from  2f  feet  to  3^  feet  deep,  by  means 
of  seven  perforators,  which  were  then  filled  with  gun- 
powder cartridges,  and  the  rock  blasted.  As  the  rock  was 
more  homogenous  and  easier,  on  the  whole,  to  work  along 
the  southern,  or  Italian  portion  of  the  tunnel,  the  heading 
on  that  side  was  carried  on  more  quickly  than  on  the  French 
side,  so  that  the  two  headings  met  at  a  point  2107  yards 
nearer  the  French  end  than  the  Italian  end.  The  wall 
between  the  two  headings  was  perforated  on  Christmas 


j6        Ventilation  of  the  Mont  Cenis  Tunnel. 

Day  1870,  thirteen  years  and  one  month  from  the  com- 
mencement of  the  work  ;  and  by  the  following  day  the 
aperture  was  sufficiently  enlarged  for  the  tunnel  to  be 
traversed  from  end  to  end,  thus  uniting  France  and  Italy 
through  the  Alps. 

The  tunnel  proved  to  be  15  yards  longer  than  calcu- 
lated from  the  surveys ;  and  probably  the  error  of  I  foot 
in  level  was  due  to  this  slight  discrepancy  in  length.  The 
direction  of  the  two  headings  was  perfectly  correct,  show- 
ing with  what  great  care  the  alignment  had  been  made 
from  the  two  ends.  Though  the  tunnel  was  driven  in 
a  perfectly  straight  line,  two  short  curved  tunnels  were 
made  subsequently,  near  each  end,  to  connect  the  railway 
in  the  tunnel  with  the  approach  railways  on  each  side, 
which  have  increased  the  actual  length  of  the  tunnel 
through  which  the  trains  run  to  very  nearly  8  miles. 
From  Fourneaux  the  line  rises,  with  a  gradient  of  I  in  43^-, 
towards  the  centre  of  the  tunnel,  to  make  up  for  the  lower 
level  of  the  Fourneaux  end  ;  and  it  falls  from  the  summit 
level  towards  Bardonneche  just  sufficiently  to  provide  for 
the  efflux  of  the  water  dripping  into  the  tunnel.  Some 
attempt  has  been  made  to  improve  the  ventilation  of  the 
tunnel  by  supplying  compressed  air,  through  an  8-inch 
pipe,  from  the  Bardonneche  end,  which  can  be  let  out  by 
means  of  cocks  where  required,  and  by  drawing  out  foul 
air  by  means  of  exhausters  at  the  Fourneaux  end.  The 
main  ventilation,  however,  is  due  to  the  natural  current 
of  air  generally  found  in  the  tunnel,  resulting  partly  from 
differences  in  atmosphere  pressure  at  the  two  ends,  subject 
frequently,  from  their  positions,  to  different  meteorological 
conditions,  partly  from  the  greater  heat  towards  the  centre 
of  the  tunnel  tending  to  induce  a  draught,  and  sometimes 
from  wind. 


Temperatures  in  the  Mont  Cenis  Tunnel.      77 

The  highest  temperature  observed  in  the  Italian  por- 
tion of  the  tunnel,  during  construction,  was  85°  near  the 
centre  of  the  tunnel.  This  is  a  much  lower  temperature 
than  would  result  from  the  increase  in  temperature  of 
i°  for  each  50  to  60  feet  in  depth  below  sea  level,  which 
has  been  observed  in  some  places,  considering  that  the 
highest  part  of  the  mountain  directly  over  the  tunnel  is 
50/6  feet  above  the  rail  level.  This  observed  increase  in 
temperature,  however,  is  due  to  the  gradual  approach 
towards  the  molten  mass  forming  the  central  core  of  the 
earth  ;  whilst  the  rocks  pierced  by  the  Mont  Cenis  Tunnel 
are  further  removed  from  this  heated  mass  than  at  the 
sea  level,  though  the  great  depth  below  the  surface  has 
caused  them  to  retain  to  some  extent  their  original  internal 
heat.  The  actual  opening  of  the  Mont  Cenis  Railway  for 
traffic  took  place  towards  the  close  of  1871,  about  a  year 
after  the  headings  of  the  tunnel  were  joined. 

The  St  Gothard  Tunnel. — Within  a  year  of  the  com- 
pletion of  the  Mont  Cenis  Railway,  a  still  more  formid- 
able enterprise  was  undertaken,  consisting,  in  addition 
to  the  heavy  approach  railways,  of  a  tunnel  g\  miles  in 
length,  and  at  a  stiil  greater  depth  below  the  surface 
than  the  Mont  Cenis  Tunnel,  namely  5733  feet  from  the 
level  of  rails  to  the  highest  point  of  the  ridge  immedi- 
ately above  the  tunnel.  The  driving  of  the  tunnel  from 
each  end  was  commenced  in  September  1872;  and  the 
boring  of  the  holes  for  blasting  was  begun  by  hand  till 
the  machines  could  be  got  ready.  The  machine  drills 
were  set  to  work  at  the  northern  end  in  April  1873,  and 
at  the  southern  end  in  July  1873.  The  advanced  head- 
ings were,  in  this  case,  carried  out  along  the  top  of  the 
tunnel ;  and  the  enlargements  were  made  first  sideways, 


78  Progress  of  St  Got  hard  Tunnel. 

and  then  downwards.     The  greatest  advance  at  both  ends 
in  a  month  was  53  yards  by  hand  labour,  and  304  yards 
with  the  machines.     The  rock  drills  of  improved  types 
were  driven,  as  at  Mont  Cenis,  by  compressed  air,  ob- 
tained by  aid  of  water  power  at  each  end  of  the  tunnel. 
The  advanced  heading  was  about  8  feet  2\  inches  square ; 
and  its  face  was  bored  with  about  twenty-six  holes,  from 
3f  to  4  feet  in  depth,  which  were  charged  with  dynamite 
cartridges,  and  exploded  in    three  operations,  from  the 
centre  outwards.     The  strata  traversed  consisted  mainly 
of  granite,  schist  and  gneiss,  with  veins  of  other  rocks  in- 
tervening in  places.     The   nature  of  the  strata   encoun- 
tered varied,  accordingly,  somewhat  frequently,  and  also 
their  condition  ;  and  the  chief  difficulty  in  boring  was  ex- 
perienced where  a  variation  in  condition  caused  the  drill 
to   diverge  sideways   to   the  softest   rock,  and  thus  jam 
itself  in  the  hole.     The  headings  were  joined  on  the  29th 
of  February  1880,  being  seven  years  and  five  months  from 
the  commencement,  or  5f  years  less  time  than  the  same 
work  occupied  at  the  Mont  Cenis  Tunnel,  though  the  St 
Gothard  Tunnel  is  if  miles  longer  than  the  other.     The 
average  daily  advance  of  the  two  headings  was  6  yards, 
in  place  of  the  2\  yards  at  the  Mont  Cenis,  showing  how 
much  the  more  general  adoption  of  drilling  machinery,  and 
its  improvements,  had  expedited  the  work.     The  driving 
of  the  advanced  heading  was  more  rapid  on  the  northern 
side,  so   that  the  junction  of  the   headings  was  effected 
613  yards  nearer  the  southern  end  than  the  northern.     A 
considerable  amount  of  water  came  into  the  tunnel,  when 
fissures  were  traversed,  during  the  progress  of  the  works, 
its  influx  being  favoured  by  the  nearly  vertical  dip  of  the 
strata ;  whereas   very  little  water  was   met   with   in  the 
Mont  Cenis  Tunnel. 


Completion  and  Temperature  of  Tunnel.        79 

The  St  Gothard  Tunnel  was  found  to  be  8^-  yards 
shorter  than  anticipated  from  the  preliminary  surveys. 
The  centre  lines  of  the  northern  and  southern  sections  of 
the  tunnel,  though  prolonged  for  over  4  miles  from  each 
extremity,  differed  only  13  inches  in  direction  at  their 
junction ;  whilst  the  error  in  level  was  only  2  inches,  ex- 
emplifying a  second  time  the  great  accuracy  which  can 
be  attained  in  these  long  underground  operations.  As 
the  difference  in  level  of  the  extremities  of  the  approach 
railways  on  each  side  is  only  1 1 8  feet,  it  was  quite  easy 
to  allow  for  this  by  a  gentle  rising  gradient  from  Goe- 
schenen  to  the  summit  level  near  the  centre  of  the  tunnel, 
whilst  providing  a  sufficient  fall  from  the  summit  to 
Airolo  for  drainage.  Owing  to  slight  modifications  of 
the  tunnel  at  each  end,  to  facilitate  the  connections  with 
the  approach  railways,  the  actual  length  of  the  tunnel 
traversed  by  trains  is  9^  miles.  Though  the  headings 
were  joined  early  in  1880,  the  tunnel  was  not  actually 
completed  and  ready  for  traffic  till  the  beginning  of 
1882,  as  a  longer  interval  was  required  between  the 
driving  of  the  top  heading  and  the  completion  of  the 
enlargement  to  the  full-sized  tunnel,  than  with  the  bottom 
heading  adopted  in  the  Mont  Cenis  Tunnel. 

The  temperature  of  the  rock  near  the  centre  of  the 
tunnel,  before  the  junction  of  the  headings,  was  naturally 
greater  than  at  the  Mont  Cenis,  owing  to  the  greater  dis- 
tance from  the  surface,  combined  with  a  lower  summit 
level,  the  highest  temperature  observed  having  reached 
87^°.  Since,  however,  the  opening  of  a  free  passage  for 
the  air  from  end  to  end,  the  temperature  fell  as  much  as 
12°  in  2^  years.  The  high  temperature  experienced  dur- 
ing construction  was  very  trying  to  the  workmen,  in  a 
damp  atmosphere,  and  with  inadequate  ventilation ;  though 


8o  Ventilation  of  St  Got  hard  Tunnel. 

the  ventilation  in  the  headings  was  gradually  improved 
by  introducing  a  better  supply  of  air  from  the  air  com- 
pressors, and  by  using  compressed  air  engines  for  remov- 
ing the  excavated  rock,  which  furnished  fresh  air  in  place  of 
the  oppressive  smoke  of  ordinary  locomotives.  The 
general  ventilation  of  the  tunnel  is  mainly  dependent  on 
the  current  produced  by  differences  of  atmospheric  pressure 
at  the  two  ends ;  though  when  this  fails,  some  fresh  air  may 
be  obtained  by  workmen  in  the  tunnel  from  a  pipe,  laid 
along  the  tunnel,  filled  with  compressed  air. 

The  St  Gothard  Tunnel  was  not  only  executed  more 
rapidly  than  the  Mont  Cenis  Tunnel,  but  also,  by  help  of 
the  experience  gained  in  the  earlier  work,  it  cost  only 
£142  per  lineal  yard,  instead  of  the  £224  per  lineal  yard 
paid  for  the  Mont  Cenis  Tunnel. 

The  Arlberg  Tunnel. — A  third  tunnel  has  been  driven 
under  the  Alps  at  the  Arl  Mountain,  which,  though 
shorter  than  its  predecessors  at  the  Mont  Cenis  and  St 
Gothard,  possesses  the  interest  of  greater  rapidity  in  con- 
struction, combined  with  a  smaller  cost  in  proportion  to 
its  length.  This  tunnel,  driven  in  a  perfectly  straight 
line,  is  6J-  miles  long,  and  was  commenced  in  July  1880, 
only  five  months  after  the  junction  of  the  advanced 
headings  of  the  St  Gothard  Tunnel.  The  boring  was 
effected  by  hand  during  the  first  four  months,  whilst  the 
drilling  machinery  was  being  prepared  ;  and  the  progress 
was  naturally  slow  during  this  period.  However,  as 
soon  as  the  machines  were  set  to  work,  they  completed 
the  driving  of  the  headings  in  the  short  space  of 
three  years  ;  for  the  headings  were  joined  in  November 
1883,  only  3-3-  years  from  the  commencement,  giving  an 
average  rate  of  progress  of  nearly  2  miles  a  year.  Similar 


Construction  of  A  rib  erg  Tunnel.  81 

drills  were  employed  to  those  used  for  the  tunnelling  on 
the  St  Gothard  Railway ;  but  whilst  a  percussion  drill, 
worked  by  compressed  air,  was  employed  at  the  eastern 
heading,  a  grinding  rotary  drill,  worked  by  water  pressure, 
was  used  at  the  western  heading.  The  rock  traversed  by 
the  tunnel  is  quartzous  schist  approximating  to  gneiss,  and 
mica  schist,  so  that  the  strata  somewhat  resemble  those  at 
the  St  Gothard.  The  rate  of  progress  at  both  headings  to- 
gether averaged  a  little  over  10  feet  a  day  during  the  three 
years  of  work  with  the  machines.  The  method  adopted  of 
driving  the  advanced  heading  along  the  bottom,  and  then 
making  shafts  upwards  at  intervals,  so  as  to  reach  the 
roof  and  form  an  upper  gallery,  which  could  be  advanced 
in  both  directions,  enabled  the  enlargement  to  the  full  size 
and  the  lining  of  the  tunnel  to  follow  close  upon  the  heading. 
The  railway  was  given  a  rising  gradient  of  i  in  72  in 
the  tunnel  from  Langen,  at  the  western  end,  to  the 
summit,  to  make  up  for  the  higher  level  of  St  Anton,  at 
the  eastern  end,  and  a  falling  gradient  of  I  in  520  from  the 
summit  to  St  Anton,  to  ensure  drainage  on  that  side  of 
the  summit.  Owing  to  the  shorter  length  of  the  tunnel, 
and  the  smaller  depth  below  the  surface,  than  in  the  previ- 
ous Alpine  tunnels,  the  internal  temperature  was  moderate, 
the  highest  temperature  of  the  rock  observed  being  66^°, 
so  that  no  serious  inconvenience  in  construction  was  experi- 
enced from  this  source.  The  railway  was  opened  for  traffic 
in  September  1884,  only  four  years  and  two  months  after 
the  commencement  of  the  works.  The  tunnel  cost  about 
£108  per  lineal  yard,  being  a  considerable  reduction  on  the 
cost  of  the  St  Gothard  Tunnel,  and  less  than  half  the  propor- 
tionate cost  of  the  Mont  Cenis  Tunnel,  and  in  fact  a  rate'of 
cost  which  has  been  attained  by  tunnels  of  the  ordinary 

kind  constructed  by  the  aid  of  shafts  through  softer  strata. 

F 


82         Route  of  proposed  Simplon  Railway. 

Proposed  Simplon  Tunnel. — It  is  possible  that  a  fourth 
tunnel  may  be  constructed ;  for  the  project  of  a  railway 
across  the  Simplon,  which  was  first  proposed  in  1859,  has 
recently  been  revived,  and  has  met  with  a  good  deal  of 
approval.  The  route  has  been  carefully  surveyed,  and  the 
scheme  reported  on  ;  and  the  railway,  according  to  the 
most  recent  plans,  would  start  from  Visp,  in  the  Rhone 
valley,  and  terminate  at  Domo  D'Ossola,  in  Italy,  with  a 
total  length  of  only  about  30  miles.  The  gradients  would 
not  exceed  I  in  50  on  the  short  north-western  slope,  and 
I  in  40  on  the  longer  south-eastern  slope,  descending  to 
the  plains  of  Italy;  but  a  tunnel  about  10  miles  long 
would  be  required.  This  tunnel,  laid  out  so  as  to  form 
two  straight  lines,  meeting  near  the  centre  at  an  angle,  in 
order  to  avoid  passing  under  greater  mountain  heights, 
would  nevertheless  be  6895  feet  below  the  surface  at  the 
highest  point,  more  than  1000  feet  greater  depth  than  the 
St  Gothard.  The  internal  heat  would  therefore  be  pro- 
bably greater,  especially  as  the  tunnel  would  be  at  a  lower 
level  ;  and  this  has  been  estimated  at  a  maximum  of  100° 
to  104°  in  the  central  portion,  which  it  is  considered  might 
be  made  bearable  for  the  workmen  by  special  arrange- 
ments for  ventilation,  and  for  cleansing  and  cooling  the  air 
near  the  faces  of  the  advanced  headings.  The  summit 
level  of  the  line  inside  the  tunnel,  as  designed,  would  be 
only  2773  feet  above  sea  level,  lower  even  than  the 
summit  of  the  Semmering  Railway,  which  is  the  lowest 
of  the  existing  Alpine  lines,  and  1720  feet  lower  than 
the  summit  of  the  Brenner  Railway.  This  lower  level 
would  render  the  Simplon  railway  easier  than  either  the 
Mont  Cenis  or  St  Gothard  lines  ;  and  this  route  would 
also  shorten  the  distance  between  Paris  and  Milan,  and 
between  Boulogne  and  Brindisi.  The  cost  of  the  long 


Prospects  of  Simplon  Railway.  83 

tunnel,  which  would  occupy  about  one-third  of  the  whole 
length  of  line  to  be  constructed,  has  been  estimated  at 
little  more  per  lineal  yard  than  the  Arlberg  Tunnel,  even 
after  making  special  allowances  for  ventilation  and  re- 
duction of  any  extreme  central  internal  temperature. 
The  only  apparent  objections  that  could  be  raised  against 
this  scheme  are,  the  uncertainty  as  to  the  heat  that  may 
be  encountered  at  a  depth  below  the  surface  1160  feet 
greater  than  i-n  the  St  Gothard  Tunnel,  and  at  a  level 
1010  feet  nearer  sea  level,  and  to  that  extent  nearer  to 
the  internal  heat  of  the  earth  ;  and  the  doubt  whether  the 
traffic  between  Europe  and  Italy  would  be  adequate  to 
provide  a  reasonable  return  on  the  capital  cost  of  another 
Alpine  railway,  considering  that  the  Simplon  line  could 
only  share  the  traffic  at  present  possessed  by  the  Mont 
Cenis  and  St  Gothard,  offering  merely  greater  facilities  to 
certain  districts  of  north-western  Europe.  The  question 
of  internal  heat,  however,  has  received  very  careful  con- 
sideration ;  it  was  correctly  predicted  for  the  St  Gothard 
Tunnel ;  and  it  is  not  regarded  by  experts  as  an  insuper- 
able objection.  As  regards  cost,  it  might  be  worth  while 
for  France  to  subscribe  largely  to  the  Simplon  Railway, 
without  looking  to  any  direct  return,  in  order  to  regain 
some  of  the  trade  diverted  from  her  by  the  St  Gothard 
Railway. 

Two  other  projects  for  an  Alpine  railway,  to  compete 
with  the  St  Gothard  in  the  interests  of  France,  have  been 
proposed,  one  under  Mont  Maudit,  of  the  Mont  Blanc 
range,  and  the  other  under  the  Col  de  Ferret,  near  the 
Great  St  Bernard  Pass.  The  Mont  Blanc  scheme,  how- 
ever, connecting  Bonneville  and  Aosta,  whilst  laid  out  with 
easy  gradients,  and  a  summit  level  intermediate  between 
the  proposed  Simplon  and  the  St  Gothard  summit  levels, 


84  Schemes  for  Alpine  Railways. 

would  involve  a  tunnel  I  \\  miles  long,  at  a  depth  of  9800 
feet  below  the  highest  point  traversed.  The  Great  St 
Bernard  scheme,  going  from  Martigny  to  Aosta,  would  rise, 
by  long,  circuitous,  and  steep  approach  railways  on  each 
side,  to  a  summit  level  of  the  great  height  of  over  5300  feet 
above  the  sea,  800  feet  higher  than  the  Brenner  Railway  ; 
but  the  tunnel  at  the  summit  would  be  barely  6  miles  long, 
with  a  maximum  depth  below  the  surface  of  only  3480  feet. 
Neither  of  these  schemes  compares  favourably  with  the 
proposed  Simplon  route;  for  an  excessive  heat  would 
probably  be  experienced  in  the  construction  of  the  long 
Mont  Blanc  tunnel,  at  an  unprecedented  depth  below  the 
highest  ridge  traversed  ;  and  the  long,  steep  approaches 
of  the  Great  St  Bernard  scheme,  reaching  an  altitude  con- 
stantly exposed  to  snow  drifts,  would  render  it  unsuitable 
for  a  competing  line.  Moreover,  both  these  lines,  though 
well  situated  for  diverting  traffic  from  the  Mont  Cenis 
Railway,  would  not  follow  nearly  as  suitable  a  direction 
as  the  Simplon  Railway  for  competing  for  the  traffic  of 
the  St  Gothard  Railway,  which  is  the  main  object  con- 
templated in  the  promotion  of  another  Alpine  railway  to 
the  west  of  the  St  Gothard. 


CHAPTER    V. 

THE  DETROIT,  HUDSON,  MERSEY,  AND  SEVERN  TUNNELS, 
THE  THAMES  SUBWAYS,  AND   THE  SARNIA  TUNNEL. 

THE  tunnels  under  the  Alps,  described  in  the  last  chapter, 
presented  great  difficulties  on  account  of  the  length  of 
the  tunnels,  the  hardness  of  the  rocks  pierced,  the  internal 
heat  encountered,  and  the  deficiency  of  ventilation. 
There  is,  however,  another  class  of  tunnels,  passing  under- 
neath rivers,  in  the  execution  of  which  still  greater  and 
more  unforeseen  difficulties  have  to  be  overcome.  In  the 
Mont  Cenis  Tunnel  the  main  obstacles  were  the  hardness  of 
the  strata,  and  the  absence  of  experience  in  boring  machin- 
ery ;  but  the  progress  having  been  greatly  accelerated  in  the 
later  Alpine  tunnel  works,  there  only  remain  the  internal 
heat  and  the  need  of  ventilation,  impediments  which  are 
known  and  can  more  or  less  be  provided  against.  In 
subaqueous  tunnels,  on  the  contrary,  though  the  mere  ex- 
cavation presents  little  difficulty,  the  works  are  constantly 
liable  to  an  inrush  of  water  from  an  unknown  source, 
and  in  an  unknown  volume,  as  the  headings  are  pushed 
forward.  It  might  naturally  be  supposed  that  this  danger 
would  be  threatened  from  the  river  water  overhead  ;  but  ex- 
cept in  the  case  of  the  Thames  Tunnel,  which  was  carried 
across  at  only  a  slight  depth  below  the  river  bed,  and 
the  Hudson  River  Tunnel,  traversing  silt,  the  water  has 
generally  come  in  from  land  springs,  and  not  from  the  river. 


86  First  Subaqueous  TunneL 

The  earliest  example  of  a  tunnel  carried  under  a  river 
was  the  notable  Thames  Tunnel,  between  Rotherhithe 
and  Wapping,  regarded  at  the  time  of  its  execution  as  a 
marvellous  achievement,  and  remarkable  for  the  difficulties 
encountered  in  its  construction.  The  work  was  commenced 
in  1825,  by  sinking  a  shaft  on  the  Surrey  shore,  50  feet  in 
diameter  and  80  feet  deep,  from  which  the  tunnel,  1200  feet 
long,  was  driven  through  a  bed  of  clay,  the  top  of  the  arch 
being  about  16  feet  below  the  bed  of  the  river.  Defects 
in  the  upper  layer  of  clay  led  to  the  irruption  of  the  river 
into  the  tunnel  in  1827,  when  the  work  had  reached 
544  feet  from  the  shaft,  and  again  in  1 828.  These  accidents, 
together  with  financial  difficulties,  delayed  the  completion 
of  the  tunnel  till  1843,  when  it  was  opened  for  foot  pass- 
engers. The  cost  of  the  tunnel  amounted  to  £1137  Per 
lineal  yard,  being  a  much  larger  cost  per  unit  of  length 
than  any  of  the  Alpine  tunnels.  Though  the  tunnel  was 
made  with  a  double  roadway  for  vehicles,  the  necessary 
approaches  were  never  constructed  ;  and  only  foot  pass- 
engers made  use  of  it  till  the  East  London  Railway  pur- 
chased it  in  1 866,  for  the  purpose  of  forming  a  connection  be- 
tween the  railways  north  and  south  of  the  river  at  that  part. 

The  serious  accidents,  the  long  period  occupied  in  con- 
struction, the  cost,  and  the  financial  results  of  the  Thames 
Tunnel,  offered  little  more  encouragement  to  schemes  of 
subaqueous  tunnels  than  the  unsuccessful  attempts  previ- 
ously made  to  carry  out  similar  works  under  the  Thames 
by  Mr  Trevethick,  in  1807,  at  Rotherhithe,  and  under  the 
Severn  at  Newnham. 

The  two  tunnels  at  Chicago,  made  under  the  Chicago 
River,  in  1867-71,  to  afford  improved  communication  across 
the  river,  were  really  constructed  in  the  open  air,  on  the 
'cut  and  cover'  principle,  byenclosing  thesite  within  a  coffer- 


Tunnels  under  Chicago  River.  87 

dam  across  one-half  of  the  river  at  a  time.  Tunnelling, 
also,  for  railways  in  Japan  under  rivers  whose  channels  have 
been  gradually  raised  above  the  surrounding  plains  by  the 
silting  up  of  their  beds  and  the  raising  of  embankments 
on  each  side  against  floods,  has  been  carried  out  by  tem- 
porary diversions  of  the  river  channels.  These  instances, 
accordingly,  of  tunnels  under  rivers,  are  not  strictly  ex- 
amples of  subaqueous  tunnelling.  The  construction, 
however,  of  the  East  London  Railway,  at  a  level  suitable 
for  passing  in  the  Thames  Tunnel  under  the  Thames, 
necessitated  the  formation  of  approach  tunnels  on  each 
side ;  and  the  tunnel  on  the  northern  side  had  to  pass 
under  the  East  Dock  of  the  London  Docks.  Two  tunnels, 
also,  5  and  7  feet  in  diameter,  were  successively  made,  in 
1864-67  and  1872-74,  extending  2  miles,  and  2  miles 
83  yards  respectively,  from  Chicago,  through  blue  clay 
Under  Lake  Michigan,  for  the  purpose  of  supplying 
Chicago  with  water  from  -the  lake,  drawn  off  at  a  sufficient 
distance  from  the  town  to  avoid  pollution,  through  a 
vertical  shaft  sunk  at  the  outer  extremity  of  each  tunnel. 
The  success  of  the  first  of  these  tunnels  led  to  the  con- 
struction of  a  similar  tunnel  for  the  water  supply  of  Cleve- 
land, Ohio,  extending  to  a  distance  of  i£  miles  under  Lake 
Erie.  This  tunnel,  commenced  in  1869,  proved  a  trouble- 
some work,  owing  to  layers  of  sand  met  with  in  the  clay  ; 
and,  on  one  occasion,  sand  and  water  poured  into  the 
heading  in  such  quantities,  through  a  seam,  that  the  end 
of  the  heading  had  to  be  bricked  up  and  abandoned,  and 
the  direction  of  the  tunnel  altered.  A  peculiarity  attending 
these  tunnel  works  was  the  influx  of  a  natural  inflammable 
gas,  which  occasionally  could  be  lit  at  its  point  of  issue 
with  impunity ;  but  this  gas  sometimes  appeared  in 
such  quantities  that  on  one  occasion  some  men  were 


88          Difficulties  of  Subaqueous  Tunnels. 

suffocated   by   it,   and   on    another   a   violent   explosion 
resulted  from  lighting  a  match. 

Recent  subaqueous  tunnelling  operations  have-not  in- 
variably proved  as  successful  as  the  above-mentioned  lake 
tunnels ;  for,  out  of  the  five  railway  tunnels  passing  under 
rivers,  commenced  in  the  last  twenty  years,  only  three  have 
been  brought  to  a  successful  termination,  namely,  the 
Mersey,  the  Severn,  and  the  St  Clair  tunnels.  The  Detroit 
River  Tunnel,  and  the  Hudson  River  Tunnel  both  remain 
submerged,  unfinished  works;  but  they  illustrate  very 
clearly  the  difficulties  and  uncertainties  attendant  upon 
tunnels  passing  under  rivers  which  can  neither  be  partially 
dammed  off  nor  temporarily  diverted.  In  subaqueous 
tunnels,  in  addition  to  the  tunnel  itself,  exposed  during 
construction,  from  its  low-lying  situation,  to  the  inrush  of 
springs,  a  small  drainage  tunnel  has  to  be  made  to  remove 
the  water  flowing  down  the  descending  gradients  to  the 
centre  of  the  tunnel ;  and  long  approach  tunnels  have  to 
be  constructed  at  each  end,  in  order  to  bring  the  railway 
up  to  the  surface,  from  under  the  centre  of  the  river. 

The  Detroit  River  Tunnel. — A  tunnel  under  the  Detroit 
River,  flowing  from  Lake  St  Clair  to  Lake  Erie,  was  com- 
menced in  1872,  with  the  object  of  connecting  the  Michigan 
Central  Railway  with  the  Great  Western  Railway  of 
Canada.  The  total  length  of  the  tunnel,  as  designed,  was 
to  be  if  miles,  of  which  a  little  over  half-a-mile  had  to  be 
constructed  under  the  river.  There  was  to  be  a  minimum 
depth  of  20  feet  of  material  between  the  top  of  the  brick- 
work of  the  tunnel  and  the  bed  of  the  river,  12  feet  of 
which  consisted  of  stiff  clay.  It  was  decided  to  drive  two 
independent  circular  tunnels,  i8£  feet  inside  diameter,  for 
the  up  and  down  lines ;  and  a  drainage  tunnel,  below  the 


Tunnel  under  Detroit  River.  89 

main  tunnels,  was  to  be  formed  right  across  the  river,  with 
the  object,  not  merely  of  draining  the  main  tunnels,  but 
also  of  expediting  the  construction  of  these  tunnels  by 
upward  shafts,  so  as  to  increase  the  number  of  faces  from 
which  the  tunnels  could  be  advanced.  The  drainage 
tunnel  was  commenced  from  each  bank,  on  the  completion 
of  the  shafts,  in  June  1872.  When,  however,  an  advance 
of  250  feet  had  been  made  from  the  Canadian  side,  an 
irruption  of  sand  mixed  with  water  took  place,  from  a 
seam  of  sand  in  the  clay,  which  had  been  pierced.  Though 
this  influx  of  sand  gradually  exhausted  itself,  and  was 
cleared  away,  other  similar  irruptions  took  place,  which 
could  only  be  arrested  by  erecting  bulkheads  across  the 
tunnel ;  and  the  difficulties  and  cost  became  so  great,  that 
the  work  was  not  carried  further  than  between  300  and 
400  feet  from  the  Canadian  shore.  On  the  Detroit  side, 
the  work  was  carried  out  without  much  difficulty  up  to 
i no  feet  from  the  shore;  but  from  this  point,  up  to 
1 2  20  feet  from  the  shore,  nearly  half  way  across,  the  in- 
flux of  water  greatly  increased,  and  though  attempts  were 
made  to  push  forward  the  main  tunnel  by  means  of  upward 
shafts,  the  works  were  eventually  abandoned  in  1873. 

The  Hudson  River  Tunnel. — New  York  is  separated 
from  the  mainland  to  the  west  by  the  Hudson  River,  so 
that  communication  with  Jersey  City,  and  the  railways 
going  to  the  west,  is  effected  by  ferries.  As  the  river  is 
about  a  mile  in  width,  and  60  feet  deep,  and  the  bed 
is  composed  of  silt,  the  erection  of  a  bridge  would  involve 
great  difficulties  and  cost.  A  tunnel  was  accordingly 
decided  upon,  to  be  carried  through  the  silt  by  the  aid  of 
compressed  air,  following,  as  in  all  subaqueous  tunnels, 
the  slope  of  the  river  bed,  and  therefore  descending  to- 


90  Hudson  River  Tunnel  Air- Lock. 

wards  the  centre,  with  nowhere  less  than  a  depth  of  1 5  feet 
of  silt  over  the  crown  of  the  arch.  The  work  was  begun, 
in  1874,  by  sinking  a  shaft  on  the  New  Jersey  side  of 
the  river,  30  feet  inside  diameter,  to  a  depth  of  60  feet ; 
but  this  preliminary  work  was  stopped  for  five  years,  owing 
to  litigation,  soon  after  its  commencement.  When  the 
sinking  of  the  western  shaft  was  completed,  and  the  bottom 
concreted,  an  air-lock  was  placed  near  the  bottom,  and 
an  opening  was  formed  in  the  side  of  the  shaft,  from  which 
a  temporary  approach  to  the  site  of  the  tunnel  was 
formed  by  a  series  of  iron  rings,  so  as  to  get  beyond  the 
adjacent  silt,  disturbed  by  the  sinking  of  the  shaft,  before 
commencing  the  actual  tunnel.  The  air-lock  is  an 
arrangement  invariably  employed  in  connection  with 
compressed  air,  for  providing  a  method  of  communi- 
cation between  the  outer  air  and  the  chamber  filled  with 
compressed  air.  It  consists  of  a  small  airtight  room 
with  two  doors,  placed  at  the  entrance  to  the  com- 
pressed air  chamber,  into  which  compressed  air  can  be 
admitted  and  subsequently  let  out.  To  gain  admission 
to  the  compressed-air  chamber,  a  gang  of  workmen 
enter  the  air-lock  by  the  outer  door,  which  is  then 
closed  ;  and  compressed  air  being  then  introduced  into 
the  air-lock,  till  the  pressure  is  the  same  as  in  the 
chamber,  the  inner  door  can  be  opened,  and  the  work- 
men pass  into  the  chamber.1  A  reverse  process  enables 
them  to  return  again  into  the  outer  air,  or  in  this  instance 
into  the  shaft  of  the  tunnel.  The  tunnel  was  commenced 
at  the  end  of  the  connecting  chamber  by  building  out  seg- 
ments of  iron  rings  as  the  excavation  in  front  proceeded, 

1  Men  can  work  without  injury  to  health  in  compressed  air,  provided  they 
are  in  a  healthy  condition,  and  are  temperate  ;  but  the  work  under  pressure 
is  more  fatiguing  than  in  the  open  air. 


Construction  of  Hudson  Tunnel.  91 

2^  feet  long,  fastened  to  the  adjacent  inner  ones,  the  upper 
ones  being  pushed  on  in  advance  like  a  hood,  so  as  to  form 
a  roof  over  the  excavations  at  the  face ;  and  the  lower  ones 
were  then  gradually  added  as  the  excavation  was  carried 
down  till  the  ring  was  completed,  four  or  five  incomplete 
upper  segments  being  always  fixed  in  advance.  When  four 
rings  were  thus  finished,  the  silt  was  cleared  out  of  them,  and 
a  circular  ring  of  brickwork  was  built  round  the  inside,  thus 
completing  10  feet  in  length  of  the  tunnel.  The  excavation 
in  front  was  removed  in  benches  or  steps,  the  excavation 
being  carried  forward  in  advance  at  the  top ;  and  the  silt 
and  water  were  prevented  coming  into  the  work  by  the 
compressed  air,  which  also  supported  the  iron  rings  against 
external  pressure.  Two  tunnels  were  driven  parallel  to 
one  another,  for  the  two  lines  of  railway,  in  preference  to 
one  large  one.  The  progress,  after  a  short  time,  averaged 
nearly  5  feet  of  completed  tunnel  per  day.  The  works 
were  lighted  by  arc  electric  lights.  The  northern  of  the 
two  tunnels  had  been  extended  300  feet  from  the  New 
Jersey  shaft,  the  south  tunnel  was  in  progress,  and  pre- 
parations were  being  made  for  putting  in  the  permanent 
entrance  from  the  shaft  to  the  completed  tunnel,  in  place 
of  the  temporary  connecting  chamber,  when,  in  July  1880, 
about  ten  months  after  the  resumption  of  the  work,  a  leak 
occurred  at  the  junction  of  the  shaft  with  the  connecting 
chamber,  the  water  finding  a  way  through  the  loose  filling 
adjoining  the  outer  sides  of  the  shaft,  overlying  the  silt, 
which  had  been  drawn  downwards  with  the  shaft  in  its 
descent.  Some  of  the  roof  at  the  junction  consequently 
fell,  and  jamming  the  inner  door  of  the  air-lock,  barred  the 
exit  of  twenty  men  in  the  connecting  chamber ;  and  the 
water  rushed  in,  drowning  the  entombed  men,  and,  passing 
through  the  slightly  open  inner  door  of  the  air-lock,  soon 


92  Pilot  Tube  for  forming  Tunnel. 

filled  the  shaft,  the  outer  door  having  been  opened  by  six 
men  in  the  air-lock  to  effect  their  escape.  Attempts  to 
pump  the  water  out  of  the  shaft  proved  unavailing,  so  a 
timber  caisson,  or  diving-bell,  open  at  the  bottom,  and  made 
watertight  above  with  lead  and  asphalt,  was  lowered  along- 
side the  shaft.  The  caisson  was  filled  with  compressed  air, 
and  could  be  entered  from  above  by  two  small  shafts  and 
air-locks ;  it  was  gradually  lowered  on  to  the  connecting 
chamber  by  excavating  the  material  from  under  its  edges. 
This  is  the  ordinary  method  of  employing  compressed  air 
for  putting  in  the  foundations  of  bridge  piers  or  quay  walls 
in  rivers,  where  the  water  cannot  be  excluded  from  the 
site.  The  novelty  in  the  work  was  using  compressed  air 
for  effecting  excavations  horizontally  for  the  tunnels. 
In  October,  three  months  after  the  accident,  the  caisson 
reached  the  connecting  chamber,  which  was  then  cleared 
out ;  the  old  air-lock  in  the  shaft  was  reached  and  put 
right,  and  a  permanent  piece  of  tunnel  was  built  con- 
necting the  shaft  with  the  two  single  line  tunnels. 
This  very  difficult  piece  of  work  having  been  successfully 
completed,  the  tunnels  could  be  again  carried  forward 
As,  however,  the  variable  nature  of  the  silt  rendered  it 
impossible  to  carry  on  the  iron  rings,  forming  the  outer 
framework  of  the  tunnel,  in  a  perfectly  straight  line,  an 
iron  pilot  tube,  about  60  feet  long,  composed  of  rings 
4  feet  long  and  6  feet  in  diameter,  built  up  in  ten  segments, 
was  advanced  about  30  feet  in  front  of  the  tunnel  heading, 
its  rear  being  supported  by  the  finished  work.  The  rings 
for  the  tunnel  were  then  kept  in  line,  as  they  were  built 
out,  by  being  strutted  against  this  tube  with  radial  braces. 
The  excavated  material  was  conveyed  in  small  trucks  to 
the  shore  end  of  the  tunnels,  where,  being  tipped  into  a  hole 
and  mixed  with  water  it  was  ejected  through  a  pipe,  by  aid 


Advancement  of  Hudson  Tunnel.  93 

of  the  air  pressure,  to  the  surface,  and  removed.  The 
north  tunnel  had  reached  1550  feet,  and  the  south  tunnel 
570  feet  from  the  New  Jersey  side,  and  the  work  was  pro- 
ceeding rapidly  and  satisfactorily,  when  it  had  to  be 
stopped,  in  November  1882,  for  want  of  funds. 

The  work  on  the  New  York  side  of  the  river  was  only 
commenced  in  July  1881  ;  and  profiting  .by  the  experience 
gained  on  the  New  Jersey  side,  a  caisson  was  sunk  for  a 
starting  point  for  the  two  tunnels,  in  preference  to  a  shaft. 
The  first  part  of  the  tunnels  on  this  side  had  to  be  driven 
through  gravel  and  sand  which,  being  much  less  tenacious 
than  silt,  could  not  be  kept  in  position  by  compressed  air 
alone.  Accordingly,  an  iron  bulkhead,  or  shield,  had  to 
be  placed  against  the  face  of  the  heading,  being  gradually 
extended  from  the  top  downwards  as  the  excavation  was 
carried  down,  and  strongly  strutted.  The  top,  sides,  and 
bottom,  were  lined  as  before  with  iron  rings,  which  had  to 
be  reduced  in  width  to  ij  feet  to  diminish  the  tempor- 
arily exposed  portion  in  putting  the  segments  in  place. 
The  tunnels  were  carried  forward  in  lengths  of  10  to 
1 2  feet  at  a  time  ;  and  as  soon  as  the  brickwork  was  com- 
pleted, the  bulkhead  was  advanced  piecemeal  for  closing 
the  face  of  the  next  length.  A  blow  out,  or  escape  of  the 
air  under  pressure,  took  place  in  August  1 882,  a  plate  in 
the  iron  bulkhead  being  forced  out,  owing  to  the  air  find- 
ing a  vent  during  the  construction  of  a  section  of  the 
tunnel  of  the  unusual  length  of  15  feet.  The  pressure 
being  thus  reduced,  the  water  rushed  in,  and  the  workmen 
escaped  by  the  air-lock.  On  partially  expelling  the  water 
by  a  fresh  admission  of  air,  the  disturbed  plates  were  re- 
placed, and  work  resumed.  The  north  tunnel  had  been 
carried  forward  147  feet  from  the  caisson  on  the  New 
York  side,  and  the  south  tunnel  23  feet,  when  the  work 


9  j.  Subaqueous  Tunnelling  in  Silt. 

was  stopped  on  this  side  for  want  of  funds,  in  July  1883. 
The  progress  through  sand  did  not  exceed  I  foot  of  com- 
pleted tunnel  per  day ;  but  as  the  sand  had  been  nearly 
traversed  by  the  north  tunnel,  the  future  progress,  in  silt, 
should  be  the  same  as  on  the  opposite  side.  The  pressure 
of  the  air  had  to  be  adjusted  according  to  circumstances  ; 
for  when  the  pressure  was  rather  too  low,  the  silt  at  the 
face  became  damp,  and  water  leaked  in ;  and  if  the  pressure 
was  too  high,  the  water  was  forced  some  way  back  from 
the  face  of  the  silt,  which  was  then  liable  to  lose  consist- 
ency, and  fall  in.  It  was  estimated  that,  if  adequate  funds 
were  available,  the  work  could  be  completed  in  2 \  years  ; 
and  operations  have  been  recently  resumed  in  the  tunnel, 
with  the  help  of  a  shield  similar  to  that  adopted  for  the 
Thames  Subways.  (See  page  107.)  Towards  the  end 
of  1890,  a  progress  of  nearly  50  feet  per  week  was  being 
maintained.  The  novelty  of  tunnelling  through  silt  and 
quicksand,  where  the  depth  of  water  overhead  attains 
60  feet  in  places,  renders  this  undertaking  peculiarly  in- 
teresting ;  the  work  exhibits  a  fresh  method  of  employ- 
ing compressed  air;  and  the  boldness  of  the  attempt, 
almost  bordering  on  the  impossible,  merits  a  successful 
termination. 

The  Mersey  Tunnel. — The  estuary  of  the  Mersey, 
which  is  very  wide  between  the  mouth  of  the  river 
Weaver  and  the  Sloyne,  flows  in  a  comparatively  narrow 
deep  rock-bound  channel  between  Liverpool  and  Birken- 
head.  The  only  connection  formerly  between  these  two 
adjacent  towns  was  either  by  ferry  across  the  river,  or 
by  a  very  circuitous  railway  journey  round  by  Runcorn, 
where  a  bridge  crosses  the  river  at  a  narrow  point.  In 
order  to  provide  regular  railway  communication  between 


Progress  of  the  Mersey  Tunnel.  97 

the  towns,  and  to  connect  the  lines  converging  to  both  the 
towns  and  separated  by  the  river,  a  scheme  for  a  tunnel 
under  the  river  at  this  part  was  designed,  which  was 
authorised  by  Parliament  in  1866.  The  bed  of  this  narrow 
portion  of  the  estuary,  underlying  a  surface  layer  of  sand 
and  clay,  is  sandstone  rock,  a  very  good  material  for 
tunnelling  in,  and  one  which,  though  porous,  has  in  this 
case  its  surface  pores  choked  by  sand  and  silt.  The  only 
possible  unfavourable  contingencies  were  the  existence  of 
some  fissure  in  the  rock  forming  the  river  bed,  or  the 
tapping  of  extensive  land  springs  by  the  land  portions  of 
the  tunnel.  No  works  were  undertaken  till  December 
1879,  when  a  small  experimental  tunnel  was  commenced, 
to  test  the  continuity  of  the  new  red  sandstone  across  the 
river.  On  the  satisfactory  completion  of  this  preliminary 
work,  in  1 88 1,  the  regular  works  were  commenced.  Shafts 
were  sunk  on  the  two  shores  down  to  170  feet  from  the 
surface,  a  sufficient  depth  to  draw  off  the  water  from  the 
drainage  tunnel,  which  had  to  be  formed  below  the  main 
tunnel,  with  an  adequate  fall  from  the  centre  towards  each 
shaft,  so  as  to  keep  the  tunnel  dry.  (See  section,  page  96.) 
The  distance  between  these  shafts  is  I  mile  10  yards,  and 
between  the  quay  walls  on  each  side,  or  the  actual  width 
of  the  estuary  at  the  site,  three-quarters  of  a  mile.  Pumps 
were  placed  in  both  of  the  shafts,  and  served  to  keep  the 
works  dry  during  their  construction,  and  to  drain  the  tunnel 
since  its  completion.  The  drainage  tunnel,  7  to  8  feet  in 
diameter,  was  first  driven  from  each  shaft,  rising  towards 
the  centre  with  gradients  of  I  in  500  and  I  in  900 ;  and 
more  water  was  encountered  under  the  land  than  under 
the  river.  The  Liverpool  drainage  tunnel  was  driven  by 
hand,  at  an  average  rate  of  about  1 1£  yards  per  week  ;  and 
the  Birkenhead  drainage  tunnel  was  driven  by  a  Beaumont 

G 


98  Construction  of  Mersey  Tunnel. 

boring  machine,  giving  an  average  weekly  advance  of  14-5- 
yards.  The  two  portions  of  the  drainage  tunnel  were 
joined  at  1115  yards  from  the  Birkenhead  shaft,  with  a 
divergence  of  only  2\  inches  between  the  two  lines.  The 
regular  tunnel  was  then  constructed,  26  feet  wide  and  23 
feet  high.  To  obtain  a  minimum  thickness  of  material  of 
30  feet  above  the  tunnel,  at  a  place  where  the  depth  of 
the  river  at  high-water  of  spring  tides  attains  100  feet,  it 
was  necessary  for  the  tunnel  to  descend  from  the  shafts 
with  gradients  of  I  in  27  to  I  in  30  on  the  Liverpool  side, 
and  of  i  in  30  on  the  Birkenhead  side ;  whilst  it  rises  with 
somewhat  gentler  gradients  to  the  surface  on  the  further 
sides  of  the  shafts.  The  portion  under  the  centre  of  the 
river,  for  about  2\  furlongs,  has  been  given  only  just  suffi- 
cient fall  from  the  centre  for  drainage.  A  bottom  heading 
(see  note  on  page  74)  was  driven  along  the  line  of  the 
tunnel,  the  water  draining  to  the  drainage  tunnel  through 
bore  holes;  and  at  the  same  time  several  upward  openings 
in  the  roof  of  the  heading,  or  '  breakups '  as  they  are 
termed,  enabled  several  faces  to  be  worked  at  the  same 
time.  At  one  place,  near  the  Liverpool  shore,  the  top  of 
the  tunnel  emerges  3  to  6  feet  out  of  the  sandstone,  in  an 
old  main  channel  of  the  river,  for  a  distance  of  66  yards ; 
but  as  the  stratum  reached  was  mainly  clay,  and  there  is  a 
thickness  of  70  feet  of  material  intervening  between  the 
tunnel  and  the  river  at  that  part,  only  somewhat  additional 
care,  timbering  at  the  top  in  advance  in  short  lengths,  and 
a  thicker  arch,  were  required  to  carry  the  tunnel  across 
this  gap  in  the  rock.  One  fissure  only  was  traversed,  near 
the  centre,  filled  with  sandstone,  debris,  and  clay  ;  and  the 
adjacent  rock  was  somewhat  broken. 

For  the  local  traffic  between  Liverpool  and   Birken- 
head, it  was  important  to  have  stations  nearer  the  river 


Ventilation  and  Cost  of  Mersey  Tunnel.       99 

than  the  points  where  the  inclines  from  the  river  tunnel 
emerge  into  the  open  air.  Accordingly,  a  station  was 
formed  on  each  side,  in  the  rock,  a  little  landwards  of  the 
pumping  shafts,  having  the  rail  level  on  the  Liverpool 
side,  92  feet,  and  on  the  Birkenhead  side,  103  feet  below 
the  surface,  A  flight  of  steps  and  three  hydraulic  lifts 
provide  access  for  passengers  between  each  station  and 
the  street  above.  Each  lift,  worked  by  water  under 
pressure,  can  convey  100  passengers,  and  perform  the 
journey  in  about  half-a-minute. 

The  ventilation  of  the  tunnel  is  effected  by  two  fans 
on  each  shore,  worked  by  steam  engines.  The  fresh  air, 
which  enters  at  both  the  underground  stations  down  the 
shafts  affording  access  to  the  stations,  is  drawn  by  these 
fans  to  openings  situated  about  midway  on  each  side  of 
the  stations,  where  the  foul  air  enters  air  drifts,  bored 
through  the  rock,  and  passes  to  the  fans.  A  continuous 
current  of  air  is  thus  maintained  in  the  tunnel  by  the 
suction  of  air  caused  by  the  fans,  passing  in  both  direc- 
tions from  the  two  underground  stations,  which  are  thus 
constantly  supplied  with  fresh  air,  to  the  ventilating 
passages  leading  to  the  fans. 

The  actual  tunnel  is  rather  over  \\  miles  in  length; 
but,  including  a  covered  way  in  shallow  cutting  beyond 
Birkenhead,  the  railway  passes  underground,  without  a 
break,  for  more  than  2  miles.  The  portion  of  the 
railway  extending  from  a  junction  at  Birkenhead  with 
the  London  and  North-Western,  and  Great  Western 
railways  to  Church  Street,  Liverpool,  about  3  miles 
long,  was  opened  in  February  1886,  a  little  more  than 
six  years  after  the  commencement  of  the  works, 
having  cost  £500,000  per  mile.  The  total  proposed 
length  of  the  Mersey  Railway,  joining  other  lines  on  the 


ioo         Site,  and  Object  of  Severn  Tunnel. 

Cheshire  side,  connecting  the  railways  of  the  docks  on 
both  sides  of  the  river,  and  terminating  at  the  Central 
Station,  Liverpool,  is  5^  miles ;  but  only  3^  miles  are  in 
operation. 

The  Mersey  Tunnel  possesses  the  interest  of  being 
the  first  subaqueous  tunnel  of  importance  designed  and 
opened  for  railway  traffic,  though  the  Thames  Tunnel 
preceded  it  in  being  used  by  a  railway,  and  the  Severn 
Tunnel  was  commenced  earlier ;  it  is  also  the  first  tunnel 
under  a  large  river  which  has  not  been  submerged  at  any 
period  of  its  construction,  owing  to  the  capital  material 
through  which  it  passes. 

The  Severn  Tunnel. — The  river  Severn  flows  into  the 
largest  and  most  exposed  estuary  on  the  English  coast, 
with  the  highest  rise  of  tide  ;  and  this  estuary  separates 
Bristol  from  the  coalfields  of  South  Wales.  The  Severn, 
like  the  Mersey,  is  crossed  by  a  railway  bridge  at  some 
distance  from  its  mouth,  opened  in  1879,  connecting  the 
Forest  of  Dean  with  Bristol ;  and  a  steam  ferry  between 
New  Passage  and  Portskewett  gave  Bristol  its  only  direct 
access  to  the  South  Wales  Railway,  which  passes  by 
Newport,  Cardiff,  and  Swansea,  to  Milford,  and  also  to 
the  railway  going  by  Hereford  to  the  north.  The  Great 
Western  Railway  Company  had  for  a  long  time  contem- 
plated a  more  direct  and  convenient  connection  between 
their  lines,  on  each  side  of  the  estuary,  than  round  by 
Swindon  or  by  the  ferry.  They  eventually  abandoned  a 
scheme  for  a  bridge  across  the  river  near  Chepstow,  which 
they  had  obtained  powers  to  construct ;  and  in  1871  they 
decided  to  carry  a  tunnel  under  the  river  a  little  below  the 
site  of  the  ferry,  at  a  point  where  the  deep  channel  of 
the  river  is  comparatively  narrow.  The  distance  across 


Progress,  and  Flooding  of  Severn  Tunnel,      i  o  i 

the  river  at  this  site  is  a  little  over  2\  miles,  at  high-water, 
from  bank  to  bank  ;  whilst  the  main  low-water  channel  is 
only  about  2\  furlongs  wide.  The  maximum  depth  of  the 
river  at  high-water  spring  tides  is  95  feet,  the  rise  of  tide 
being  37  feet.  (See  section  page  96.) 

The  tunnel  passes  at  a  minimum  depth  of  44f  feet 
under  the  low-water  bed  of  the  river,  being  made  level  for 
a  little  over  a  furlong  under  the  deepest  channel,  and  then 
rising,  with  a  gradient  of  I  in  90  on  the  Monmouthshire 
side,  and  i  in  100  on  the  Gloucestershire  side,  till  it 
emerges  into  an  open  cutting  on  each  shore.  It  traverses 
conglomerate,  the  carboniferous  strata,  sandstones,  marl, 
and  gravel,  the  dip  of  the  strata  being  considerable. 

Work  was  commenced,  in  1873,  by  sinking  a  shaft  on 
the  Monmouthshire  side,  15  feet  in  diameter,  to  a  depth 
of  about  200  feet,  so  as  to  enable  the  whole  of  the  tunnel 
to  be  drained  from  this  point,  by  a  small  drainage  tunnel 
rising  towards  the  lowest  portion  of  the  tunnel,  under  the 
low -water  channel,  which  is  near  the  Monmouthshire 
shore.  (See  page  96.)  This  tunnel  was  commenced  as 
soon  as  the  shaft  had  been  sunk,  and  it  was  extended 
along  the  line  of  the  main  tunnel,  rising  towards  the  op- 
posite shore.  Another  shaft  was  subsequently  sunk  on 
the  Gloucestershire  shore,  and  two  more  shafts,  inland  of 
the  first  Monmouthshire  shaft ;  and  timbered  headings 
(see  note  on  page  74),  about  7  feet  square,  were  carried 
forward  in  the  line  of  the  tunnel  from  all  four  shafts.  The 
greater  portion  of  the  headings  of  the  main  tunnel  had 
thus  been  carried  out,  in  separate  sections,  with  little 
trouble  from  water,  the  first  heading  having  been  ex- 
tended nearly  2  miles  from  the  original  shaft,  when,  in 
October  1879,  an  underground  spring  was  opened  by  the 
upper  tunnel  heading,  proceeding  landwards  from  this 


IO2     Removal  of  Water  from  Severn  Tunnel. 

shaft,  about  a  furlong  and  a  half  inland.  The  water 
flowed  in  so  rapidly,  in  spite  of  every  effort  to  arrest  the 
flow,  that  the  workmen  had  to  make  their  escape  ;  and 
the  long  tunnel  heading  under  the  river  was  soon  flooded, 
the  water  pouring  down  into  it,  through  the  shaft  and  the 
drainage  tunnel,  from  the  main  tunnel  heading  on  the 
rising  Monmouthshire  slope.  Before  attempting  to  re- 
move the  water,  two  shields  of  oak  were  placed  against 
the  openings  of  the  tunnel  heading,  on  each  side  of  the 
old  shaft,  and  fixed  firmly  by  struts  across  the  shaft, 
to  stop  the  influx  from  the  spring.  The  pumps  in  the 
shaft  were  then  set  to  work,  but  did  not  succeed,  after 
numerous  breakdowns  of  the  pumps  and  fresh  attempts, 
in  lowering  the  water  within  about  25  feet  of  the 
bottom.  It  was  then  determined  to  try  to  close  a  door  in 
the  long  heading  under  the  river,  about  looofeet  from  the 
old  pumping  shaft,  which  had  been  left  open  in  the  rush  at 
the  time  the  spring  burst  out.  An  attempt  was  made  by  an 
experienced  diver  to  reach  the  door,  groping  his  way  in 
the  dark  across  the  debris  in  the  heading,  with  the  help 
of  three  other  divers  to  pass  along  his  air  tube.  He  found 
it,  however,  impossible  to  drag  along  his  tube  sufficiently 
far  to  reach  the  door.  At  last  this  diver  was  provided 
with  a  newly  invented  portable  knapsack,  containing 
compressed  oxygen,  enabling  a  diver  to  supply  himself 
with  the  necessary  gas  for  a  certain  period  under  water 
without  the  encumbrance  of  dragging  along  a  constantly 
lengthening  tube.  After  testing  the  apparatus,  on  the 
second  attempt  the  man  succeeded  in  making  his  way 
along  the  heading,  across  the  debris,  and  reached  the  door, 
which  he  shut,  closing  also  a  valve  regulating  the  flow  of 
water,  on  the  far  side  of  the  door,  and  returned  in  safety, 
after  having  been  I  hour  and  20  minutes  under  water, 


Progress,  and  Ventilation  of  Tunnel.          103 

with  no  supply  of  air  beyond  that  contained  in  his  knap- 
sack. The  water  was  then,  at  last,  removed  from  the 
workings,  after  a  submersion  of  over  a  year.  Access  was 
also  obtained  to  the  heading  leading  to  the  big  spring, 
through  a  door  in  the  shield  ;  and  a  wall  was  built  across 
this  heading,  at  a  suitable  place,  with  a  door  in  it,  which 
was  then  closed,  and  the  spring  thus  excluded  from  the 
rest  of  the  works.  A  new  shaft,  18  feet  in  diameter,  was 
sunk  on  the  Monmouthshire  shore,  a  little  in  advance  of  the 
old  one,  and  another  shaft,  for  pumping,  on  the  land  side 
of  the  spring,  with  the  object  of  keeping  down  the  water. 

After  the  flooding  of  the  works,  it  was  determined  to 
lower  the  tunnel  1 5  feet,  so  as  to  give  it  greater  security 
from  an  irruption  of  the  river.  A  new  drainage  tunnel 
had,  accordingly,  to  be  driven  below  the  original  one,  and 
the  old  tunnel  headings  became  top  headings  instead  of 
bottom  headings  ;  and,  accordingly,  for  some  distance  the 
arch  of  the  tunnel  was  built  first,  and  the  lower  part  of 
the  tunnel  was  subsequently  built  by  underpinning  on 
lowering  the  headings.  In  other  places,  the  more  ordinary 
method  of  bottom  headings,  with  ( breakups '  to  reach  the 
level  of  the  arch,  and  increase  the  number  of  faces,  was 
employed.  The  works  were  ventilated  by  a  fan  placed  at 
the  top  of  the  new  deep  shaft ;  the  rock  was  bored  by 
drills  worked  by  compressed  air  ;  the  blasting  was  effected 
mainly  with  cotton  powder,  or  tonite,  owing  to  its  com- 
parative freedom  from  obnoxious  fumes ;  and  the  works 
were  lit  by  Swan  electric  lights. 

The  lining  of  the  tunnel  with  brickwork  was  com- 
menced, in  1 88 1,  at  three  places;  and  the  long  heading 
from  the  Monmouthshire  side  was  connected  with  the 
heading  from  the  shaft  on  the  other  bank  in  September 
1 88 1.  In  the  previous  April,  however,  salt  water  came  in 


1O4         High  Tide  flooding  Severn  Tunnel. 

suddenly  through  the  roof  of  the  tunnel  at  a  point  under 
the  river,  near  the  Gloucestershire  shore,  where  the  men 
were  building  the  arch  of  the  tunnel.  This  water  was  found 
to  come  through  a  deep  hole  in  a  part  of  the  river  nearly 
dry  at  low- water.  The  hole  was  filled  with  clay,  which 
was  weighted  with  clay  in  bags  at  the  top  ;  and  the  leak 
was  thus  stopped,  and  a  thicker  arch  of  brickwork  was 
built  over  the  tunnel  at  this  place.  The  work  progressed 
without  any  special  incident  throughout  1882,  the  tunnel 
having  been  completed  for  some  distance  under  the  river 
from  the  Gloucestershire  shaft,  the  arch  completed  under 
the  main  channel,  and  the  tunnel  commenced  on  each  side 
of  the  three  shafts  in  the  Monmouthshire  approach  tunnel. 
Considerable  progress  was  made  with  the  tunnel,  from  the 
ends  of  the  completed  portions,  on  each  side  of  the  five 
shafts,  during  1883,  the  tunnel  being  completed  nearly 
half  way  across  the  river  from  the  Gloucestershire  side, 
and  the  work  under  the  main  channel  extended.  Early 
in  October  1883  however,  the  big  spring  broke  out  again, 
and  flooded  the  workings  a  second  time.  The  rush  of 
water  into  the  long  heading  under  the  river,  down  from 
the  old  shaft,  was  so  sudden  that  the  men  were  swept  along 
through  the  open  door.  The  door  was  subsequently  closed 
again  by  the  same  diver  in  the  same  manner  as  before  ;  the 
water  was  then  pumped  out,  and  the  large  spring  excluded 
in  less  than  a  month.  In  the  middle  of  October,  a  very  high 
tide  coinciding  with  a  south-westerly  gale,  the  water  rose 
above  any  previously  recorded  level,  and  overtopping  one 
of  the  inland  shafts  on  the  Monmouthshire  side,  poured 
down  into  the  headings  in  communication  with  this  shaft. 
Fortunately,  the  tide  fell  before  the  water  had  risen  within 
8  feet  of  the  arch  of  the  tunnel ;  and  eighty-three  men  at 
work  in  this  section  of  the  tunnel  took  refuge  in  the  upper 


Shutting  off  big  Spring  from  Tunnel.        105 

headings,  till  they  could  be  rescued  by  a  boat  let  down  the 
shaft,  and  launched  upon  the  subterranean  canal. 

When  the  progress  of  the  tunnel,  in  1884,  rendered  it 
necessary  to  undertake  the  portion  traversing  the  fissure  of 
the  large  spring,  a  side  heading  was  driven  to  intercept  the 
spring  at  a  lower  point,  so  that  by  diverting  the  water  into 
this  heading  the  site  of  the  tunnel  could  be  kept  dry.  As, 
moreover,  the  spring  was  fed  by  water  percolating  through 
the  fissured  bed  of  a  brook  above,  a  concrete  bed  was  formed 
for  this  brook,  along  a  length  of  4  miles.  The  final  link  of 
heading  through  this  part  was  completed  in  October  1884, 
enabling  the  tunnel  to  be  traversed  from  end  to  end  ;  and 
the  tunnel  was  practically  completed  at  the  close  of  the 
year,  with  the  exception  of  this  piece,  which  was  only 
partially  lined  with  brickwork.  The  fissure  below  the 
tunnel  was  filled  with  concrete ;  and  the  last  length  of 
the  tunnel  was  completed  in  April  1885.  An  attempt  was 
then  made  to  imprison  the  spring,  but  after  a  time  the 
pressure  of  the  confined  water  on  the  tunnel  became  so 
great  that  the  bricks  began  to  break,  and  the  water  escaped 
through  the  cracks.  Accordingly,  a  shaft,  29  feet  in  dia- 
meter, was  sunk  at  the  side  of  the  tunnel,  and  pumps  were 
erected,  in  1886,  sufficient  to  lift  the  whole  of  the  flow  of 
water  from  the  spring.  Altogether,  the  pumping  power  pro- 
vided at  this  and  other  shafts,  on  the  completion  of  the  works, 
is  able  to  raise  66  million  gallons  of  water  a  day,  which 
is  more  than  double  the  maximum  quantity  that  had  been 
pumped.  Ventilation  is  provided  by  two  fans  placed  in  the 
shafts  on  each  side  of  the  river,  one  of  the  fans  having  a  dia- 
meter of  40  feet.  The  railway  was  opened  for  traffic  in  Dec- 
ember 1 886,  the  same  year  as  the  Mersey  Tunnel,  more  than 
thirteen  years  after  the  first  commencement  of  the  works. 

The  total  length  of  the  tunnel  is  4  miles  626  yards,  and 


io6  Construction  of  Tower  Subway. 

it  is  therefore  the  longest  tunnel  in  Great  Britain  ;  and 
indeed,  after  the  Alpine  tunnels  described  in  the  last 
chapter,  and  the  Hoosac  Tunnel  in  the  United  States,  it 
is  the  next  longest  railway  tunnel  in  the  world ;  and  the 
sudden  and  unforeseen  difficulties  encountered  and  sur- 
mounted have  not  been  surpassed  in  any  other  engineering 
work.  Trains  traverse  it  in  about  seven  minutes ;  and  it  has 
already  proved  a  very  important  link  of  the  Great  Western 
Railway  system,  and  is  attracting  an  increasing  traffic. 

The  Thames  Subways. — It  is  evident,  from  the  preceding 
pages,  that  subaqueous  tunnels  often  have  a  most  event- 
ful, chequered  history  during  their  construction,  little 
dreamt  of  by  passengers  who  pass  through  them  in  com- 
fort after  their  completion.  Of  those  already  described, 
the  Mersey  Tunnel  alone  has  been  happy  in  having  no 
such  history ;  whilst  the  Thames  Tunnel,  the  pioneer  of 
this  class  of  works,  furnishes  a  striking  illustration  of  the 
difficulties  that  may  be  encountered.  Two  subways,  how- 
ever, have  been  since  carried  out  under  the  Thames  at 
London,  one  below,  and  one  above  London  Bridge,  which 
have  attracted  comparatively  little  attention  owing  to  their 
uneventful  history,  resulting  from  the  success  of  the  system 
adopted,  and  the  favourable  nature  of  the  stratum  traversed. 
The  first  of  these  subways,  known  as  the  Tower  Subway, 
crosses  under  the  Thames  near  the  Tower ;  it  was  con- 
structed in  1869,  traversing  the  London  clay  underlying 
the  alluvial  deposit  in  the  bed  of  the  river.  The  subway 
was  driven  from  two  shafts  sunk  from  a  convenient  place 
on  each  bank,  behind  the  wharves  and  buildings  abutting 
on  the  river,  down  into  the  London  clay,  to  depths  of 
about  63  feet  and  56  feet  respectively  below  the  surface. 
The  subway  consists  of  a  cast-iron  tube,  7  feet  inside 


Tunnelling  under  tfa  Thames.  107 

diameter,  formed  by  a  series  of  rings  composed  of  three 
segments  bolted  together..  It  slopes  down  to  the  centre, 
where  there  is  a  thickness  of  material  of  22  feet  between 
the  tube  and  the  river  bed  ;  and  the  length  of  the  subway 
is  a  quarter  of  a  mile. 

The  construction  of  the  subway  was  effected  by  means 
of  a  shield,  pushed  forward  by  six  screws,  following  close 
upon  a  short  heading  excavated  in  front  of  it  to  prepare 
for  its  advance ;  and  the  successive  rings  were  put 
together  under  the  shelter  of  the  rear  portion  of  the  shield, 
which  supplies  the  place  of  timbering.  The  shield  con- 
sisted of  a  circular  wrought-iron  tube,  slightly  larger  in 
diameter  than  the  rings  forming  the  subway,  with  a  sort  of 
strengthened  cutting  edge  in  front,  and  partially  closed 
near  the  outer  end  by  a  diaphragm  of  iron  plates,  leaving 
a  central  aperture  for  the  passage  of  the  men  excavating 
ahead  of  it,  and  through  which  the  excavated  material  was 
thrown  back,  to  be  removed  by  a  skip,  or  little  truck, 
running  on  a  small  tramway  laid  along  the  finished  portion 
of  the  subway.  The  total  length  of  the  shield  was  4-^  feet, 
of  which  2f  feet  at  the  rear  were  quite  clear  of  the 
diaphragm  and  stiffening  plates,  and  provided  a  protect- 
ing lining  to  the  heading,  under  the  shelter  of  which  the 
cast-iron  rings  forming  the  subway  were  put  in  place, 
each  ring  having  a  width  of  only  \\  feet.  The  vacant 
space,  of  i  inch  round  the  outside  of  the  rings,  left  by  the 
advance  of  the  shield  was  filled  up  by  injecting  liquid  lias 
lime  through  little  holes  purposely  provided  in  the  rings, 
so  as  to  guard  against  any  settlement  of  the  surrounding 
clay.  The  works  were  commenced  in  February  1869,  and 
completed  in  the  following  November.  A  tramcar  drawn 
by  a  rope  along  the  subway,  and  hydraulic  lifts  in  the 
shafts,  were  originally  provided  for  the  conveyance  of 


io8     Construction  of  South  London  Subway. 

passengers;  but  as  the  working  expenses  exceeded  the 
receipts,  these  conveniences  were  removed ;  and  the 
subway  serves  as  a  passage  for  foot  passengers,  with 
staircases  in  each  shaft 

This  second  tunnel  under  the  Thames  furnishes  a  strik- 
ing contrast,  as  regards  rate  of  progress,  to  the  old  Thames 
Tunnel,  owing,  in  a  great  measure,  to  its  passing,  at  a 
greater  depth  from  the  surface,  through  undisturbed,  homo- 
geneous London  clay,  owing  also  to  the  simpler  and  more 
rapid  method  of  progress  for  a  comparatively  small  under- 
taking, and  to  freedom  from  delays  through  want  of  funds. 
The  Tower  Subway,  however,  resembles  the  Thames 
Tunnel  (closed  to  foot  passengers  in  1869)  in  attracting 
only  a  small  number  of  people  beyond  workmen,  morn- 
ing and  evening,  going  to  and  returning  from  their  work. 

Another  larger  double  subway  has  been  recently 
constructed  under  the  Thames,  a  little  higher  up, 
forming  a  portion  of  the  City  and  South  London  Railway, 
designed  to  connect  Clapham  and  Kennington  directly 
with  the  city,  by  a  subterranean  tramcar  service,  worked 
by  electricity,  opened  between  the  city  and  Stockwell  in 
November  1890.  This  subway  consists  of  two  adjacent 
cast-iron  tubes,  formed  with  rings,  10  feet  in  diameter  and 
if  feet  in  width,  composed  of  six  segments  and  a  key 
piece  at  the  top  ;  and  it  has  been  driven  through  the 
London  clay  by  a  similar  method  to  that  adopted  for  the 
Tower  Subway.  The  cutter  at  the  front  end  of  the  shield 
is  of  steel  ;  and  the  shield  is  pushed  forward  by  six  hy- 
draulic presses.  The  rate  of  progress  has  averaged  1 3  feet 
a  day,  and  a  maximum  of  16  feet  has  been  attained. 
The  portion  under  the  river,  which  was  carried  out  three 
or  four  years  ago,  was  accomplished  without  difficulty, 
and  was  remarkably  free  from  water ;  indeed,  less  water 


Tunnel  in  America,  ^mder  St  Clair  River.     109 

was  found  there  than  at  several  other  points  along  the 
route,  compressed  air  having  been  required  in  one  place, 
when  piercing  a  layer  of  gravel,  to  keep  back  the  water. 
Access  to  the  subway,  about  50  feet  below  the  surface, 
is  provided  at  the  stations,  by  lifts  working  in  large  shafts. 

Sarnia  Tunnel,  under  St  Clair  River. — The  boundary 
between  Canada  and  the  United  States,  from  Lake 
Huron  to  Lake  St  Clair,  is  formed  by  the  River  St 
Clair  which  connects  these  two  lakes.  A  tunnel  has 
been  constructed  under  this  river,  2017  yards  in  length, 
to  connect  the  Grand  Trunk  Railway  of  Canada,  at 
Sarnia,  with  the  United  States  Railways  at  Port  Huron. 
The  tunnel  traverses  650  yards  on  the  Canadian  side ;  it 
then  passes  for  a  length  of  767  yards  under  the  River  St 
Clair,  and  terminates  at  a  distance  of  600  yards  beyond 
the  American  bank  of  the  river.  It  consists  of  a  cast-iron 
tube,  21  feet  in  diameter,  built  up  in  segments,  and  lined 
inside  with  masonry,  providing  accommodation  for  a 
single  line  of  railway.  The  tunnel  was  driven  from  each 
end  through  blue  clay,  within  the  shelter  of  a  shield 
pushed  forward  by  hydraulic  pressess,  and  by  the  aid  of 
compressed  air,  in  a  similar  method  to  the  Thames 
Subways.  This  Sarnia  Tunnel,  opened  in  1890,  has 
superseded  the  ferry  which  formerly  served  as  the  means 
of  communication  between  the  railways  of  Canada  and 
the  United  States  at  this  point ;  and  it  is  the  first  sub- 
aqueous tunnel  which  has  been  completed  in  America. 

The  Channel  Tunnel. — A  much-talked-of  submarine 
tunnel  has  been  proposed  for  some  years  past,  designed 
to  traverse  the  chalk  stratum  under  the  English  Channel, 
at  the  straits  of  Dover,  so  as  to  connect  England  with  the 
Continent  by  railway.  The  continuity  of  the  chalk 


I  io         Investigations  for  Channel  Tunnel. 

between  the  two  coasts  has  been  tested,  as  far  as  practic- 
able, by  comparing  the  strata  on  each  side,  as  ascertained 
by  borings,  and  by  bringing  up  samples  of  the  chalk 
bottom  from  various  points  across  the  Channel.  Shafts, 
also,  have  been  sunk  on  the  English  and  French  shores, 
and  experimental  headings  driven  to  determine  more 
exactly  the  nature  of  the  chalk  to  be  traversed  ;  and  a 
heading,  from  a  shaft  between  Folkestone  and  Dover,  has 
been  carried  2000  yards  under  the  sea.  Two  companies 
have  been  formed  for  undertaking  the  work  ;  but  owing  to 
political  considerations,  and  questions  of  military  expedi- 
ency, parliamentary  sanction  has  been  withheld. 

The  feasibility  of  the  scheme  depends  upon  the  absence 
of  any  large  fissures  in  the  chalk  in  the  line  of  the  tunnel, 
which  can  only  be  determined  with  absolute  certainty  by 
driving  a  heading,  or  small  tunnel,  right  across  under  the 
Channel.  The  whole,  however,  of  the  indications  obtained 
from  the  various  investigations  give  promise  of  continuity 
and  compactness  in  the  chalk.  The  shortest  distance  across 
the  straits  is  about  21  miles  ;  but  one  of  the  routes  proposed 
would  be  23^  miles  from  shore  to  shore  ;  and  two  or  three 
miles  additional  would  be  required  on  each  side  to  reach 
the  level  of  the  existing  lines,  so  as  to  form  a  junction 
with  them.  The  submarine  tunnel,  accordingly,  between 
the  shafts  on  each  shore,  would  be  from  21  to  23^  miles 
long,  without  any  intervening  shafts.  The  continuous 
tunnel  would  therefore  be  more  than  double  the  length 
of  the  longest  Alpine  tunnel ;  but  chalk  is  perhaps  the  best 
material  in  which  a  tunnel  can  be  made  ;  and,  with  control 
of  the  water,  rapid  progress  could  be  effected.  Besides 
the  great  cost,  the  ventilation  of  the  tunnel  would  probably 
constitute  one  of  the  chief  difficulties.  The  depth  of  water 
in  mid-channel,  at  low-water,  is  from  160  to  190  feet;  and 


Design,  and  Feasibility  of  Channel  Tunnel.     1 1 1 

the  least  thickness  of  chalk  over  the  tunnel  would  be 
between  100  and  200  feet.  The  tunnel  would  descend 
from  each  shaft,  with  gradients  not  exceeding  I  in  80,  till 
a  suitable  depth  is  reached  in  the  chalk;  and  it  would 
then  ascend  towards  the  central  point,  with  gradients  of 
i  in  1000,  to  drain  the  tunnel  from  the  centre  to  the  end 
of  these  gradients,  where  drainage  tunnels,  with  down- 
ward gradients  to  the  shafts,  would  convey  away  the  water 
to  be  raised  by  pumps  at  the  shafts.  These  drainage 
tunnels  would  have  to  be  first  constructed  to  drain  the 
main  tunnel  during  its  progress ;  and  they  would  serve  also 
afterwards  as  ventilation  conduits,  for  drawing  the  foul  air 
away  from  the  centre  of  the  tunnel  towards  the  shafts. 

Apart  from  considerations  of  political  expediency,  in 
relation  to  the  piercing  of  the  silver  streak  which  guards 
our  shores,  there  is  apparently  no  insuperable  impediment 
to  the  construction  of  the  Channel  Tunnel,  owing  to  the 
favourable  nature  of  the  stratum  to  be  traversed.  A  suit- 
able return  on  the  large  capital  expenditure  may  appear 
doubtful ;  but  this  is  not  a  matter  which  concerns  the 
general  public,  if  a  company  is  prepared  to  undertake  the 
risk.  Moreover,  if  the  large  expenditure  on  the  Mersey 
and  Severn  tunnels,  and  the  Forth  Bridge,  should  prove 
adequately  remunerative,  an  outlay  of  three  or  four  times 
the  cost  of  the  last-named  work  would  not  appear  ex- 
cessive for  securing  the  whole  of  the  traffic  between  Great 
Britain  and  the  Continent.  It  is  quite  possible  that,  in 
spite  of  the  element  of  uncertainty  which  must  always 
surround  subaqueous  operations,  the  Channel  Tunnel 
might  be  constructed  with  much  less  difficulty  than  some 
of  the  tunnels  described  in  the  present  chapter ;  and  the 
magnitude  of  the  work,  and  its  position,  would  unquestion- 
ably make  it  rank  as  one  of  the  wonders  of  the  world. 


CHAPTER   VI. 

THE   PROGRESS  AND   PRINCIPLES   OF   MODERN 
BRIDGE  CONSTRUCTION. 

THE  ordinary  method  of  carrying  a  railway  across  a  river 
is  by  means  of  a  bridge,  where  all  the  work,  with  the  ex- 
ception of  the  foundations  for  the  piers  and  abutments,  is 
above  ground,  and  in  the  construction  of  which  the  un- 
certainties and  risks  attending  subaqueous  tunnels  are 
avoided.  Accordingly,  subaqueous  tunnels  have  only 
been  resorted  to  where  the  conditions  of  the  site  render 
it  impracticable  or  inexpedient  to  erect  a  bridge  across 
a  river  or  estuary.  As  it  is  desirable,  in  crossing  a  navigable 
river,  to  impede  the  navigation  as  little  as  possible,  and  as 
in  many  cases  piers  in  the  alluvial  deposit  of  the  river  bed 
are  costly  and  difficult  to  construct,  the  spans  of  river 
bridges,  especially  across  the  deeper  portion  of  the  river, 
are  made  as  large  as  practicable,  consistent  with  due  regard 
to  cost 

PROGRESS   OF  BRIDGE   CONSTRUCTION. 

The  earliest  bridges  were  made  of  wood ;  and  arched 
masonry  bridges  were  subsequently  adopted  for  most  large 
spans,  previous  to  the  introduction  of  iron  for  bridge 
building  in  the  last  century.  Masonry  bridges,  however, 
have  not  attained  very  large  spans ;  for  the  Alma  Bridge 


Spans  of  large  A  re  tied  Bridges.  1 1 3 

at  Paris,  over  the  Seine,  built  of  concrete,  has  a  central 
span  of  141^  feet;  London  Bridge,  152  feet;  Grosvenor 
Bridge,  over  the  Dee  at  Chester,  a  span  of  200  feet ;  and 
Trezzo  Bridge,  over  the  Adda,  251  feet,  which  appears  to 
be  the  largest  span  of  any  masonry  arched  bridge  hitherto 
built.  Curiously  enough,  one  or  two  timber  bridges  have 
been  built  with  larger  spans,  the  wooden  Schaffhausen 
Bridge,  across  the  Rhine,  destroyed  in  1799,  having  had 
a  span  of  193  feet;  a  wooden  bridge,  over  the  Connecticut 
River  at  Hanover,  in  the  United  States,  built  in  1796,  had 
a  single  arch  of  236  feet ;  whilst  the  Wittingen  timber 
bridge,  built  in  1758,  and  destroyed  by  fire  about  the  be- 
ginning of  the  century,  had  a  span  of  390  feet.  Cast-iron 
was  introduced  for  arched  bridges  towards  the  end  of  the 
last  century,  the  first  bridge  of  this  construction,  100  feet 
in  span,  having  been  erected  across  the  Severn,  near  Coal- 
brookdale,  in  1779.  A  larger  bridge,  formed  of  cast-iron, 
was  built  across  the  Wear  at  Sunderland  in  1796,  with 
a  single  arch  of  236  feet  span  ;  and  Southwark  Bridge, 
with  a  central  arch  of  240  feet,  was  erected  in  1819. 
These  cast-iron  bridges,  however,  though  cheaper  than 
masonry  bridges,  and  applying  a  purely  compressive 
strain  to  the  cast-iron,  which  it  is  specially  fitted  to 
sustain,  do  not  exceed  the  spans  of  masonry  bridges. 

One  or  two  suspension  bridges  were  erected  in  the 
last  century  ;  but  the  first  notable  example  of  a  suspension 
bridge  of  large  span  was  the  Menai  Suspension  Bridge, 
erected  in  1819-25,  for  carrying  a  road  across  the  Menai 
Straits,  to  facilitate  communication  with  Anglesea,  and 
thence  to  Ireland.  This  bridge  has  a  span  of  570  feet 
between  its  points  of  support,  and  affords  a  headway  in 
the  centre  above  high-water  of  102  feet.  This  principle 
of  suspension  has  since  been  extended  to  a  number  of 

H 


1 14        Large  Spans  of  Suspension  Bridges. 

road  bridges,  amongst  the  most  notable  of  which  are  a 
bridge  at  Budapest,  over  the  Danube,  having  a  span  of 
666  feet,  erected  in  1842-49;  the  Freiburg  Bridge,  in 
Switzerland,  erected  in  1833-4,  across  the  valley  of  the 
Sarine,  having  a  span  of  870  feet,  and  situated  at  a  height 
of  167  feet  above  the  river;  and  the  Clifton  Suspension 
Bridge,  crossing  the  precipitous  valley  of  the  Avon  below 
Bristol,  at  an  elevation  of  250  feet  above  high-water,  with 
a  span  of  702  feet.  The  Clifton  Bridge  was  erected  in 
1862-4,  the  chains  of  the  old  Hungerford  Suspension 
Bridge  having  been  used  for  a  portion  of  the  chains  of  the 
Clifton  Bridge,  when  the  Hungerford  foot-bridge  was 
superseded  by  the  Charing  Cross  Railway  Bridge.  A 
suspension  bridge  also,  nearly  half-a-mile  in  length,  crosses 
the  Dnieper  at  Kieff,  having  four  principal  spans  of 
440  feet,  which  was  erected  in  1851. 

Timber  trusses,  masonry  and  brick  arches,  and  cast- 
iron  arches  and  girders,  were  employed  for  the  earlier  rail- 
way bridges.  When,  however,  a  bridge  with  large  spans 
was  required  for  carrying  the  Chester  and  Holyhead 
Railway  across  the  Menai  Straits,  a  new  departure  was 
made  in  bridge  construction  by  Mr  Robert  Stephenson. 
A  suspension  bridge  like  Telford's  road  bridge  was 
deemed  unsuitable,  owing  to  the  oscillations  set  up  in  an 
ordinary  bridge  of  that  type  by  a  heavy  rapidly  moving 
load.  One  design  proposed  consisted  of  a  cast-iron 
bridge,  having  two  arches,  and  a  central  pier  built  on  the 
Britannia  rock  in  mid-channel,  on  which  the  central  pier 
of  the  present  structure  stands.  After  numerous  experi- 
ments, however,  for  ascertaining  the  strength  of  wrought- 
iron,  particularly  in  the  form  of  tubes,  it  was  determined 
to  carry  the  railway  across  the  Straits  in  wrought-iron  tubes, 
with  cellular  roof  and  floor  forming  the  top  and  bottom 


Britannia,  and  Conway  Tubular  Bridges.     1 1 5 

flanges  of  these  girders.  This  bridge,  well  known  as  the 
Britannia  Tubular  Bridge,  consists  of  two  parallel  rectangu- 
lar tubes,  one  for  the  up,  and  the  other  for  the  down  line, 
with  two  central  spans  of  459  feet,  and  two  shore  spans  of 
230  feet,  affording  a  clear  headway  of  103!  feet  above  high- 
water  of  spring  tides  in  both  the  channels  on  each  side  of 
the  central  rock.  (See page  134.)  The  four  tubes  for  the 
central  spans  were  floated  into  position,  and  gradually 
raised  by  hydraulic  presses  to  the  required  height,  the  sup- 
porting masonry  of  the  piers  being  built  up  underneath,  as 
no  scaffolding  was  permitted  to  be  erected  in  the  channel. 
This  bridge  was  commenced  in  1846,  and  opened  for  traffic 
in  1850.  A  similar  tubular  bridge,  with  a  single  span  of 
400  feet,  was  erected  about  the  same  time  for  carrying  the 
same  railway  across  the  Conway  River  at  Conway,  by  the 
side  of  another  roadway  suspension  bridge  erected  by  Tel- 
ford  for  the  Chester  and  Holyhead  road;  and  it  was  opened 
in  1848.  Another  much  longer  bridge  of  the  same  type 
was  erected  across  the  S*t  Lawrence  at  Montreal  in  1854-59. 
This  railway  bridge,  nearly  if  miles  long,  has  one  central 
span  of  330  feet,  and  twenty-four  side  spans  of  242  feet ; 
and  it  has  piers  with  specially  shaped  cutwaters  up  stream 
to  protect  the  bridge  on  the  breaking  up  of  the  ice  in 
spring.  The  Britannia  Tubular  Bridge  is  of  special  interest 
as  being  the  first  instance  of  a  wrought-iron  girder  bridge  ; 
but  without  detracting  at  all  from  the  merits  of  the 
structure,  it  is  unquestionable  that  if  a  bridge  had  to  be 
erected  in  a  similar  position  at  the  present  day,  it  would 
not,  with  the  extended  knowledge  gained  during  the  last 
forty  years,  be  constructed  in  the  same  manner.  The 
tensile  strength  of  wrought-iron  in  the  form  of  bars  had 
long  before  been  satisfactorily  established  in  the  construc- 
tion of  the  chains  of  suspension  bridges.  The  preliminary 


i  r  6      Changes  in  Design  of  Girder  Bridges. 

experiments,  however,  for  the  tubular  bridge  proved,  and 
the  success  of  the  Britannia  Bridge  demonstrated  to  the 
world,  that  wrought-iron  plates  and  angle-irons  riveted 
together  so  as  to  form  a  beam,  or  girder,  with  strong  top 
and  bottom  flanges,  and  a  comparatively  thin  vertical  con- 
necting piece,  or  web,  could  resist  considerable  tensile 
and  compressive  strains,  and  thus  that  wrought-iron 
girders  could  bear  heavy  loads  when  merely  supported 
at  each  end. 

In  later  constructions  of  wrought-iron  girders,  the 
cellular  flanges  have  been  replaced  by  flat  plates  riveted 
together,  and  the  sides  of  the  tube  by  a  single  central  web. 
In  small  girders,  the  web  has  generally  been  made  of  a 
solid  plate  stiffened  at  intervals;  but  in  large  girders,  open 
trellis  or  lattice  work  in  various  forms,  composed  of  struts 
and  ties,  has  been  substituted  for  the  solid  web.  (See 
page  134.)  The  object  of  the  web  in  these  girders,  or 
trusses,  is  to  give  depth,  and  consequently  increased 
strength  to  the  beam ;  and  the  web  transmits  the  strains 
from  one  flange  to  the  other,  and  thus  unites  the  different 
portions  into  a  single  structure.  Innumerable  wrought-iron 
girder  bridges  of  various  dimensions  and  types  have  been 
erected  for  railways  since  the  inauguration  of  the  system 
by  the  Britannia  Bridge  ;  but  only  the  two  other  bridges 
named  above  have  been  constructed  on  precisely  the  same 
tubular  principle,  though  tubes  have  been  employed  for 
portions  of  bridges  exposed  to  compressive  strains. 

Another  wrought-iron  bridge,  having  nearly  as  large 
spans  as  the  Britannia  Bridge,  was  erected  soon  after  by 
Mr  Brunei,  across  the  river  Tamar  at  Saltash,  for  the  Ply- 
mouth and  Cornwall  Railway.  A  large  arched  tube  above 
and  suspension  chains  below,  strongly  braced  together,  carry 
the  small  girders  underneath  supporting  the  platform  of 


Various  Long- Span  Girder  Bridges.        117 

the  bridge  across  the  two  large  spans  of  455  feet,  afford- 
ing two  clear  spans  of  436  feet  between  the  piers,  and 
a  headway  of  100  feet  above  high-water  of  spring  tides. 
The  total  length  of  the  bridge,  including  several  small 
spans  on  both  sides,  is  2240  feet  ;  and  the  bridge  was 
opened  for  traffic  in  1859. 

Though  the  Britannia  and  Saltash  bridges  remained 
unrivalled  as  regards  span  in  Great  Britain  for  more  than 
thirty  years,  the  large  size  of  the  rivers  of  the  Continent 
of  Europe  and  North  America  necessitated  the  erection  of 
large  structures  for  conveying  railways  across  them,  ap- 
proaching in  many  cases  the  spans  of  these  bridges,  and 
occasionally  surpassing  them.  Thus,  amongst  wrought- 
iron  girder  bridges,  a  bridge  erected  across  the  Vistula  at 
Dirschau,  in  1856,  has  a  span  of  397  feet ;  another,  erected 
in  1 86 1,  across  the  Inn  at  Passau,  has  a  span  of  420  feet; 
another,  across  the  Rhine  at  Mainz,  erected  in  1862,  has  a 
span  of  345  feet ;  whilst  the  Kuilenberg  Bridge,  across  the 
river  Lek  in  Holland,  erected  in  1868,  has  a  span  of 
492  feet;  and  the  Moerdyk  Bridge,  completed  in  1880, 
carries  the  Antwerp  and  Rotterdam  Railway  across  the 
Hollandsch  Diep  by  fourteen  spans  of  328  feet.  In  the 
United  States,  two  bridges  were  built  across  the  Ohio  at 
Louisville,  in  1870,  with  spans  of  368,  and  396  feet  respec- 
tively, the  form  of  construction  adopted  being  the  Fink 
truss  system,  with  cast-iron  tubes  for  the  flange  in  com- 
pression at  the  top,  and  the  remainder  being  made  of 
wrought-iron,  with  no  continuous  bottom  flange.  Two 
wrought-iron  girder  bridges  were  erected  across  the  Ohio 
at  Cincinnati,  in  1872  and  1877,  with  spans  of  420,  and 
519  feet  respectively.  More  recently,  the  Henderson 
Bridge  has  been  erected,  with  a  span  across  the  main 
river  channel  of  522  feet,  and  another  bridge  over  the 


1 1 8          Instances  of  Remarkable  Bridges. 

Ohio  at  Cincinnati,  with  a  span  of  550  feet,  which  have 
the  largest  spans  of  any  discontinuous  ordinary  girder 
bridges  hitherto  constructed.  A  continuous  wrought-iron 
girder  bridge  was  built  across  the  Kentucky  River,  in 
1876-7,  having  three  spans  of  375  feet  at  a  height  of 
280  feet  above  the  river  bed.  The  Tay  Bridge,  besides 
being  memorable  on  account  of  the  overthrow  of  the 
large  spans  of  the  first  structure  by  the  wind  in  a  storm  in 
December  1879,  only  a  year  and  a  half  after  its  opening, 
is  remarkable  as  being  the  longest  girder  bridge  in  the 
world,  the  new  bridge,  built  in  1882-7,  having  a  total 
length  of  10,700  feet,  or  rather  more  than  two  miles, 
though  its  largest  openings,  eleven  in  number,  have  a 
span  of  only  245  feet.  Some  bridges  across  deep  valleys, 
though  not  having  unusual  spans,  are  worthy  of  notice 
on  account  of  the  general  light  appearance  and  graceful- 
ness of  their  construction,  of  which  the  Crumlin  Viaduct 
over  the  river  Ebbw  in  Monmouthshire,  the  Portage 
Bridge  over  the  Genesee  River  in  the  State  of  New  York, 
and  the  Trisana  Viaduct,  on  the  Arlberg  Railway,  over 
the  river  Trisana,  are  instances.  The  Crumlin  Viaduct, 
1800  feet  long,  has  ten  spans  of  150  feet  ;  and  the  height 
of  the  rails  above  the  bed  of  the  Ebbw  is  200  feet.  The 
Portage  Bridge,  in  the  United  States,  originally  constructed 
of  wood,  and  burnt  down  in  1875,  has  been  reconstructed 
in  iron.  It  has  a  total  length  of  800  feet,  having  one  span 
of  1 80  feet,  two  spans  of  100  feet,  and  seven  spans  of 
50  feet  ;  and  it  is  230  feet  above  the  river.  The  Trisana 
Viaduct. has  a  central  span  of  377  feet,  at  a  height  of 
282  feet  over  the  river,  and  two  side  spans  of  131  feet. 

The  use  of  wrought-iron  for  bridge  construction  has 
not  been  confined  to  girders  and  suspension  bridges  ;  for 
arched  bridges  have  also  been  made  of  wrought-iron,  as, 


Wrought-iron  Arches,  and  Niagara  Bridge.  1 19 

for  instance,  at  Coblentz,  where  the  Rhine  is  crossed  by 
three  arches  of  5 1 5  feet  span.  In  the  construction  of  the 
Victoria  Bridge  over  the  Thames  at  Pimlico,  commenced 
in  1859,  and  completed  in  1860,  and  also  in  its  widening, 
in  1865-6,  wrought-iron  was  preferred  to  cast-iron  for  the 
four  arches.  The  most  notable  instances,  however,  of  the 
employment  of  wrought-iron  for  arches  are  the  two 
bridges  over  the  Douro  at  Oporto,  and  the  central  span  of 
the  Garabit  Viaduct,  in  France,  over  the  river  Truyere, 
completed  in  1884.  (See  page  134.)  These  three  open- 
work arches,  built  out  from  each  side  and  joined  in  the 
centre  without  using  any  scaffolding,  have  spans  of  525 
feet,  571  feet,  and  541  feet,  and  are  raised  201  feet,  251 
feet,  and  390  feet  above  their  respective  rivers. 

Soon  after  the  completion  of  the  Britannia  Tubular 
Bridge,  the  suspension  principle,  which  had  been  con- 
sidered unsuitable  for  railway  traffic  across  the  large 
spans  of  the  Menai  Straits,  was  adopted  for  a  railway, 
connecting  Canada  with  the  United  States,  over  the 
Niagara  River,  below  the  falls,  where  the  span  required 
is  821^  feet.  An  iron  wire  cable  suspension  bridge  was 
erected  in  1852-55,  and  carries  a  railway  on  the  upper 
platform,  and  a  roadway  underneath,  at  a  height  of 
245  feet  above  the  river.  This  remarkable  bridge,  thrown 
across  a  river  in  which  no  staging  could  have  been  erected, 
is  suspended  from  four  cables,  10  inches  in  diameter,  each 
containing  3640  wires  ;  and  it  is  stiffened  by  a  series  of 
auxiliary  cables  spreading  out  from  the  towers  on  each 
bank,  and  thus  relieving  the  cables  from  the  strain  of  the 
shore  ends  of  the  bridge  for  some  distance  from  the  towers. 
Though  the  suspended  framework,  originally  made  of 
timber,  has  required  to  be  replaced  by  iron,  and  the 
towers  strengthened,  the  bridge  has  successfully  carried  the 


I2O  Brooklyn,  and  faidson  Suspension  Bridges. 

railway  traffic  for  thirty-five  years.  This  bridge  was  for 
some  time  the  only  suspension  bridge  employed  for  rail- 
way traffic,  as  well  as  the  longest  span  in  the  world.  It 
was,  however,  nearly  equalled  by  a  suspension  bridge,  of 
800  feet  clear  span,  over  the  Monongahela  River  at  Pitts- 
burgh, opened  in  1 877.  This  bridge,  however,  serves  only 
for  a  double  line  of  tramway  and  footways,  and  is  not 
more  than  80  feet  above  the  river.  The  Niagara  Bridge 
has,  in  its  turn,  been  surpassed  by  a  suspension  bridge  of 
1057  feet  span  at  Cincinnati ;  and  it  has  been  eclipsed  by 
the  Brooklyn  Bridge,  over  the  East  River  at  New  York, 
with  a  span  of  1595  feet,  designed  by  Mr  Roebling,  the 
engineer  of  the  Niagara  Bridge.  The  Brooklyn  Bridge, 
opened  in  1883,  is  the  largest  suspension  bridge  in  exist- 
ence (see  illustration) ;  and  till  the  opening  of  the  Forth 
Bridge,  in  1890,  its  span  was  the  largest  of  any  bridge 
in  the  world.  It,  however,  is  liable  to  share  the  fate  of 
most  of  the  celebrated  engineering  triumphs  of  modern 
times,  in  having  its  pre-eminence  amongst  suspension 
bridges  diminished  by  a  still  more  daring  engineering 
feat.  A  bridge  is,  indeed,  proposed  for  crossing  the 
Hudson  River  at  New  York,  which  is  designed  to  have  a 
central  span  of  2860  feet,  nearly  double  the  span  of  the 
Brooklyn  Bridge,  and  surpassing  the  two  large  spans  of  the 
Forth  Bridge  by  1 160  feet.  This  new  project  is  intended  to 
serve  the  same  purpose,  of  affording  more  direct  communi- 
cation between  New  York  and  Jersey  City,  as  the  tunnel 
in  progress  under  the  river  (see  page  89),  which  was 
originally  started  as  a  more  feasible  scheme  than  a  bridge. 
Wrought-iron,  which  gradually  superseded  cast-iron 
after  the  erection  of  the  Britannia  Bridge,  is  in  its  turn 
being  superseded  by  steel.  Cast-iron  is  much  stronger 
than  wrought-iron  in  resisting  a"  compressive  strain,  but 


Advantages  of  Steel  for  Bridges.  1 2 1 

much  weaker  in  resisting  tensile  strains ;  whilst  wrought- 
iron  is  somewhat  more  able  to  resist  tension  than  com- 
pression. Steel,  however,  is,  in  every  sense,  able  to  support 
much  greater  strains  than  wrought-iron ;  and  therefore, 
for  the  same  span,  a  lighter  bridge,  subjected  from  its 
smaller  weight  to  less  strains,  can  be  constructed  of  steel 
than  of  wrought-iron,  or  a  steel  bridge  of  larger  span  than 
an  iron  bridge  can  be  made  with  the  same  weight  of 
material.  For  some  time  the  great  varieties  of  steel,  and 
the  uncertainties  attending  its  manufacture,  checked  the 
general  adoption  of  steel  for  bridges  ;  but  the  great  im- 
provements effected  in  the  manufacture  of  steel  in  recent 
years,  and  an  extended  knowledge  of  its  qualities  and 
reliability,  as  well  as  the  reduction  in  its  cost,  have  estab- 
lished its  employment  for  large  structures.  The  St  Louis 
Bridge,  over  the  Mississippi,  constructed  in  1867-74,  was 
the  earliest  instance  of  the  adoption  of  steel  for  a  bridge 
of  large  span.  This  bridge  has  a  central  arch  of  520  feet 
span,  and  two  side  arches  of  502  feet,  formed  with  tubes 
of  cast  steel.  (See  page  134.)  Another  large  arched  steel 
bridge  has  since  been  erected  over  the  Harlem  River  at 
New  York,  with  two  spans  of  510  feet,  and  a  clear  head- 
way of  1 50  feet  under  the  centre  of  the  arch.  The  most 
notable  and  most  recent  adoption  of  steel  for  a  bridge  of 
large  span  is  the  cantilever  Forth  Bridge,  with  two  spans  of 
1700  feet,  over  the  Firth  of  Forth.  (See  illustration.) 


PRINCIPLES  OF  BRIDGE  CONSTRUCTION. 

The  preceding  pages  show  what  a  great  advance  has 
been  achieved  in  bridge  construction  within  the  last  fifty 
years.  The  Britannia  Bridge,  with  its  spans  of  459  feet, 


j  22  Effects  of  Increased  Spans. 

surpassed  all  previous  railway  bridges  ;  but  of  recent  years 
several  bridges  of  over  500  feet  span  have  been  erected. 
The  spans  of  the  Freiburg  and  Niagara  suspension 
bridges  have  been  doubled  in  the  Brooklyn  Bridge  ;  and 
the  greatest  span  of  the  Britannia  Bridge  has  been  nearly 
quadrupled  in  the  Forth  Bridge.  To  realise  fully,  how- 
ever, the  magnitude  of  this  advance,  a  brief  reference  to  the 
general  principles  of  bridge  construction  is  indispensable. 

When  an  increased  span  is  given  to  a  bridge,  the 
resulting  increased  strains  necessitate  an  enlargement  of 
the  different  parts  to  support  these  strains,  and  conse- 
quently an  increased  weight,  which,  together  with  the 
larger  load  which  a  longer  bridge  may  have  to  carry,  adds 
to  the  strains  which  the  mere  increase  in  length  involves 
Accordingly,  an  addition  to  the  span,  besides  adding  pro- 
portionately to  the  length  of  the  bridge,  and  therefore  to 
the  weight  to  be  supported,  adds  also  to  the  weight  of  the 
bridge  per  unit  of  length,  and  increases  the  possible  mov- 
ing load,  or  length  of  train,  that  can  be  on  the  bridge  at 
one  time.  The  weight  of  a  bridge  therefore,  and  conse- 
quently its  cost,  increases  much  more  rapidly  with  the 
span  than  the  mere  proportionate  addition  to  its  length. 
With  a  girder  or  arch  of  uniform  depth,  the  maximum 
strain  increases  in  proportion  to  the  total  weight  sup- 
ported multiplied  into  the  length  of  the  opening  as  the 
span  is  increased,  and  therefore  in  a  somewhat  greater 
ratio  than  the  square  of  the  span  ;  and  the  only  method 
of  reducing  this  rapid  increase  is  by  making  the  depth 
greater  with  the  increase  in  span,  as  the  strain  varies 
inversely  with  the  depth,  or,  in  other  words,  if  the  depth 
is  doubled  the  strain  on  the  flanges  is  halved.  The  exist- 
ing methods  of  spanning  large  openings  are  the  various 
forms  of  girders  or  trusses,  the  suspension  principle,  arches, 


Principles  of  Girder  Bridges.  123 

and  cantilevers,  examples  of  which  have  been  already  given. 
(See  page  134.)  It  must  be  a  matter  of  surprise  to  the  un- 
initiated to  observe,  in  comparing  these  types,  that  whilst 
suspension  bridges,  arches,  and  cantilevers  get  slighter 
from  the  abutments  towards  the  centre,  detached  girders  are 
always  made  higher,  or  their  flanges  thicker,  in  the  centre. 

Girders. — In  ordinary  girder  bridges,  supported  at 
each  end  on  abutments  or  piers,  the  bending  strain,  due 
to  the  total  weight  borne,  is  greatest  in  the  centre  of  the 
span,  tending  to  compress  the  top  flange  and  to  extend 
the  bottom  flange.  The  shearing  stress  on  the  web  or 
bars,  connecting  the  two  flanges  of  the  girder,  or  the 
transverse  strain,  tending  to  make  the  more  loaded  portion 
of  a  girder  slide  away  and  separate  from  the  less  weighted 
portion,  is  very  slight  in  the  centre,  and  increases  towards 
the  abutments,  reaching  a  maximum  close  to  either  point 
of  support.  As  the  bending  strain  diminishes  from  the 
centre  to  the  points  of  support,  the  height  of  the  girder 
may  be  gradually  reduced  towards  the  abutments,  or  the 
thickness  of  the  flanges  reduced.  On  the  contrary,  owing 
to  the  increase  of  the  shearing  stress  from  the  centre 
towards  the  ends,  the  stiffening  of  the  solid  web  has  to 
be  increased,  or  the  tension  bars  and  struts  have  to  be 
enlarged  in  section  gradually,  from  the  centre  towards  the 
extremities  of  the  girder.  Girders  have  to  support  both 
tensile  and  compressive  strains,  for  their  bottom  flange 
and  the  alternate  bars,  or  ties,  of  their  trellis  web  are  in 
tension,  whilst  their  top  flange  and  their  remaining  bars, 
or  struts,  are  in  compression.  Accordingly,  cast-iron  is 
not  a  suitable  material  for  girders,  owing  to  its  poor  capa- 
city for  resisting  tensile  strains.  Wrought-iron  and  steel, 
however,  are  well  suited  for  resisting  both  tension  and 


124        Advantages  of  Continuous  Girders. 

compression.  The  simple  discontinuous  girder  is  not  well 
adapted  for  long  spans,  for  the  maximum  central  strain 
rapidly  augments  with  the  increase  in  span,  and  the 
strength,  and  therefore  the  weight  at  the  centre,  has  to  be 
proportionately  increased.  This  may,  indeed,  be  to  some 
extent  reduced  by  an  increase  in  the  depth  of  the  girder; 
but  this  has  a  limit,  owing  to  the  necessity  of  greatly  in- 
creasing the  stiffness  of  long  struts,  to  secure  them  against 
bending  under  compressive  strains.  (Seepage  134.) 

A  simple  method  of  augmenting  the  strength  of  a 
girder  for  large  spans  is  by  making  the  girder  continuous 
over  two  or  more  spans.  In  the  simple  case  of  a  girder 
continuous  over  two  equal  spans,  the  bending  strains  are 
altered,  both  in  position  and  magnitude,  from  what  they 
are  with  two  disconnected  girders.  The  bending  strain 
becomes  a  maximum  over  the  central  pier ;  and  the  top 
flange  is  in  tension  at  this  part,  and  the  bottom  flange  in 
compression.  When  the  girder  is  uniformly  loaded,  the 
bending  strains,  decreasing  from  the  central  point,  become 
nothing  at  a  point  about  one-third  of  the  span  distant  on 
each  side  from  the  central  pier  ;  and  this  central  portion 
of  the  girder,  comprising  about  one-third  of  its  length, 
acts  as  a  sort  of  cantilever  to  the  remainder  of  the  girder 
on  each  side.  The  effective  spans  of  these  outer  portions 
of  the  girder  are  thus  practically  reduced  to  the  length 
of  these  portions,  or  about  two-thirds  of  the  actual  spans  ; 
and  the  maximum  strain  in  the  centre  of  each  of  these 
sections  of  the  continuous  girder  is  proportionately 
reduced.  Accordingly,  the  continuity  of  the  girder  places 
the  maximum  strain,  and  consequently  the  greatest 
weight,  in  the  centre  of  the  central  pier,  where  it  is  easily 
supported,  and  reduces  the  strains  on  the  end  portions  of 
the  girder,  over  the  openings,  to  those  produced  on  a  dis- 


Advantages  of  Suspension  Bridges.          125 

connected  girder  having  a  span  two-thirds  of  the  actual 
span.  In  fact,  the  effect  of  the  continuity  over  the  pier, 
on  the  two  one-third  portions  of  the  girder  at  each  end, 
is  as  if  girders  were  substituted  for  them,  resting  on 
each  abutment,  and  on  brackets  extending  out  for  one- 
third  of  the  actual  spans  on  each  side  of  the  central  pier. 
(See  Hooghly  Bridge,  page  134.)  The  strains  on  the 
central  portions  of  girders  continuous  over  more  than  two 
spans  would  be  still  more  reduced  ;  but  the  necessity  of 
providing  for  expansion  and  contraction  renders  any  great 
extension  of  the  principle  inapplicable  for  large  spans. 

Suspension  Bridges. — The  principle  of  suspension  for 
bridges  possesses  two  great  advantages,  namely,  that  every 
portion  of  the  structure  is  in  tension,  and  therefore  requires 
no  additional  strengthening,  as  in  long  struts,  to  provide 
against  bending,  and  enables  the  whole  strength  of  the 
materials  to  be  fully  utilised  ;  and  also  that,  with  wire 
cables,  which  are  used  for  very  large  spans,  the  resistance 
of  the  metal,  in  the  form  of  wire,  to  tension  is  much  greater 
than  the  average  strength  of  the  metal,  owing  to  the  great 
tensile  resistance  of  the  outer  skin  of  the  wire.  Unlike  a 
simple  girder  bridge  moreover,  the  strain  on  a  suspension 
bridge  is  least  in  the  centre  of  the  span,  increasing  towards 
the  piers ;  and  the  weight,  also,  of  the  bridge  per  unit  of 
length  is  least  in  the  centre,  and  increases  towards  the  sides, 
owing  to  the  increasing  divergence  of  the  chains  from  the 
horizontal,  and  the  greater  length  of  the  suspending  rods  on 
approaching  the  piers  from  which  the  cables  hang.  The 
anchor  cables,  which  carry  down  the  strain  of  the  supension 
cables  to  solid  anchorages  imbedded  in  the  ground  on  the 
land  side  of  the  piers,  are  a  necessary  addition  to  the  actual 
bridge  spanning  the  opening.  In  suspension  bridges,  also, 


126      Points  relating  to  Suspension  Bridges. 

which  have  smaller  shore  spans  on  the  land  side  of  the  piers, 
the  strain  on  the  main  cables  can  be  reduced  by  auxiliary 
cables  spreading  out  on  each  side  of  the  piers,  which  also 
stiffen  the  bridge,  and  are  equipoised  by  supporting  the 
land  span  on  one  side  of  the  pier  and  the  nearer  portion  of 
the  large  span  on  the  other  side.  This  arrangement  has 
been  adopted  with  advantage  at  the  Brooklyn  Bridge.  (See 
illustration.)  Even,  however,  when  the  large  span  extends 
right  across  the  opening,  as  at  the  Niagara  Bridge,  and  the 
strains  on  the  cables  have  to  be  wholly  borne  by  corre- 
sponding shore  cables,  this  form  of  bridge  is  very  economi- 
cal, and  is  well  suited  for  crossing  deep  ravines,  as  it  can 
be  erected  without  any  central  staging  between  the  piers. 
The  deflection  of  a  suspension  bridge  under  a  moving  load, 
owing  to  the  flexible  chains  modifying  their  curvature 
according  to  the  position  of  the  load,  is  of  much  less  im- 
portance in  bridges  of  large  span,  in  consequence  of  the 
small  proportion  the  moving  load  bears  to  the  fixed  load 
in  a  very  large  bridge  ;  and  it  is  also  reduced  by  the  intro- 
duction of  auxiliary  cables,  acting  as  stiffening  ties,  radiating 
from  the  piers.  A  danger  to  which  wire  cables  are  pecu- 
liarly liable  is  their  unperceived  deterioration  by  rust,  from 
moisture  penetrating  to  the  interstices  between  the  wires  ; 
but  great  precautions  have  been  taken  of  late  years  to 
guard  against  this  insidious  corrosion,  by  so  coating  the 
cables  as  to  render  them  impervious  to  wet,  and  also  by  so 
arranging  the  cables  that  the  renewal  of  a  damaged  cable 
can  be  easily  effected. 

The  dip  of  the  cables,  or  the  vertical  distance  between 
the  level  of  their  suspension  on  the  piers  and  their  lowest 
central  point,  corresponds  to  the  depth  between  the 
flanges  in  a  girder  bridge,  and  to  the  rise  of  an  arched 
bridge,  and  increases  with  the  span.  Accordingly,  the 


Arches  and  Suspension  Bridges  contrasted.  127 

height  of  the  suspension  towers  from  the  bottom  level  of 
the  bridge,  which  is  52  feet  in  the  Menai  Bridge,  is  60  feet 
in  the  Niagara  Bridge,  and  1 50  feet  in  the  Brooklyn  Bridge  ; 
whilst  the  height  of  the  towers,  as  designed  for  the  proposed 
Hudson  River  Suspension  Bridge,  is  500  feet  above  the 
water,  or  very  nearly  the  height  of  the  spires  of  Cologne 
Cathedral,  and  rising  about  380  feet  above  the  bridge. 

Arches.- — An  arch  is  the  exact  converse  of  a  suspension 
bridge ;  for  whereas  in  a  suspension  bridge  all  the  parts 
are  in  tension,  in  an  arch  all  the  parts  are  in  compression. 
The  cables  in  the  one  correspond  to  the  arched  ribs  in  the 
other ;  the  suspension  rods  are  replaced  by  the  spandrils, 
which  transmit  the  weight  of  the  roadway  to  the  arch  ; 
and  in  place  of  anchor  cables  bearing  the  tensional  strains 
of  the  cables,  there  are  solid  abutments  to  support  the 
thrust  of  the  arch.  The  parts,  however,  of  an  arched 
bridge,  being  all  in  compression,  have  to  be  given  much 
greater  rigidity  to  avoid  flexure,  and  therefore  an  arched 
bridge  is  much  heavier  and  more  costly  than  a  suspension 
bridge  of  the  same  span  ;  but,  for  the  same  reason,  it  is  less 
liable  to  deflection  under  a  moving  load.  Arched  bridges, 
also,  are  more  costly  to  erect ;  and  the  great  rise  required 
with  large  spans  would  preclude  their  adoption,  except 
across  deep  gorges,  or  over  rivers  with  high  banks.  They 
are,  moreover,  not  nearly  so  well  suited  for  being  con- 
structed without  scaffolding  ;  though  the  arched  bridges 
of  largest  span  have  had  to  be  erected  by  building  out. 
Owing  to  the  great  rise  attainable  with  arched  bridges 
'(see  page  134),  and  the  decrease  of  the  strains  from  the 
abutments  to  the  centre  of  the  arch,  the  spans  of  arched 
bridges  have  equalled,  and  even  somewhat  surpassed,  the 
spans  obtained  hitherto  with  ordinary  girder  bridges ; 


128       Bowstring  Girders,  and  Cantilevers. 

though  the  spans  of  both  those  types  of  bridge  have,  up 
to  the  present  time,  found  a  limit  between  500  and  600 
feet.  Neither  arch  nor  girder  bridges  have  as  yet  much 
exceeded  one-third  of  the  span  attained  by  the  Brooklyn 
Suspension  Bridge. 

Bowstring  girders  are  really  arches,  in  which  the  abut- 
ment is  dispensed  with  by  the  help  of  a  horizontal  tie 
connecting  the  two  extremities  of  the  arched  rib,  and 
thus  taking  its  thrust.  The  High  Level  Bridge  at  New- 
castle furnishes  a  good  example  of  this  form  of  arched 
structure  ;  and  the  Saltash  Bridge  is  similar  in  type,  the 
chains  taking  the  place  of  the  horizontal  tie.  This  arrange- 
ment converts  the  arch  into  a  self-contained  structure, 
like  a  girder,  which  can  rest  on  piers,  and  obviates  the 
necessity  of  abutments  to  sustain  the  thrust  of  the  arch. 
The  Saltash  Bridge,  however,  remains  the  longest  span  of 
this  type ;  whilst  the  simple  arch  has  been  given  increased 
spans  within  the  last  thirty  years. 

Cantilevers. — A  cantilever,1  in  the  engineering  sense,  is 
an  overhanging  bracket  or  truss.  The  word  might  pos- 
sibly be  applied  to  the  central  portion  of  a  continuous 
girder,  for  if  a  girder,  continuous  over  two  spans,  was  separ- 
ated in  imagination  into  three  equal  parts,  the  central  third 
might  be  regarded  as  a  double  bracket  or  cantilever,  sup- 
porting at  its  two  extremities  the  outer  ends  of  the  two 
other  portions,  which  actually  bear  the  same  strains  as 
independent  girders  of  the  same  length  would  be  subjected 
to.  The  term  cantilever  is,  indeed,  given  to  continuous 
girder  bridges  by  American  writers,  the  Kentucky  River 
Bridge  being  described  as  the  first  cantilever  bridge  of 
importance  erected  in  America,  though  it  is  really  a  con- 

1  Cantilever,  from  cattt,  old  French  for  angle,  and  lever,  to  raise. 


Principles  of  Cantilever  Bridges. 

tinuous  girder  bridge  of  uniform  depth  over  three  spans, 
without  any  appearance  of  a  bracket  at  the  piers.  This 
bridge,  however,  formed  a  cantilever  during  its  construc- 
tion, being  built  out  without  scaffolding  ;  and  from  this 
point  of  view  the  St  Louis,  Douro,  and  Garabit  bridges 
were  cantilevers  during  erection,  though  this  description 
ceased  to  be  applicable  on  the  completion  of  the  arches. 
The  term  cantilever  appears  to  be  only  suitable  strictly  to 
structures  which  increase  in  depth  over  their  piers,  giving 
the  appearance  of  a  bracket  with  a  symmetrical  overhang 
on  the  shore  side  of  the  pier  to  counterbalance  the  other, 
or  where  the  projecting  portions  are  really  independent  of 
the  girders  whose  ends  they  support.  (See  page  134.) 

The  principle  of  the  cantilever,  for  increasing  the  span 
of  bridges,  was  known  long  ago  ;  for  bridges  formed  with 
timbers  deeply  embedded  into  the  abutments  or  banks  on 
each  side,  and  with  central  beams  resting  on  the  ends  of 
these  timbers,  were  constructed  for  crossing  rivers  some 
centuries  ago  in  India  and  Japan  ;  but  the  application 
of  the  principle  to  metal  bridges  of  large  span  is  quite 
recent. 

The  Niagara  Cantilever  Bridge,  crossing  the  Niagara 
River  a  short  distance  upstream  from  the  Suspension 
Bridge  was  the  first  true  metal  cantilever  bridge  erected, 
having  been  opened  in  1883.  (See  page  134.)  The 
bridge  rests  upon  two  light  braced  steel  piers,  which, 
with  the  masonry  foundations,  rise  180  feet  above  the 
surface  of  the  river  on  each  bank.  Two  cantilevers,  395 
feet  in  length,  spread  out  on  each  side  of  the  piers  at 
the  top,  the  shore  portion  of  each  cantilever  forming  the 
shore  spans,  and  the  river  portions  supporting  between 
them  a  central  girder,  120  feet  in  length,  which,  together 
with  the  river  cantilevers,  spans  the  gap  of  495  feet  be- 


130  Forms  of  Cantilever  Bridges. 

tween  the  two  piers.  The  Fraser  River  Bridge  of  the 
Canadian  Pacific  Railway,  opened  in  1885,  is  a  structure 
of  similar  type,  with  a  central  opening  having  a  clear 
span  of  315  feet.  Counterpoise  weights  at  the  shore 
ends  of  the  cantilevers,  or  shore  anchorages,  enable  the 
river  ends  of  the  cantilevers  to  support  the  additional 
weight  of  the  central  girder  between  them,  with  its  propor- 
tion of  the  moving  load.  The  cantilever  system  is  speci- 
ally well  adapted  for  building  out  from  the  piers ;  for  the 
additions  on  each  side,  as  the  work  proceeds,  balance  each 
other,  and  the  shore  anchorage  counterbalances  the  half 
portion  of  the  central  span.  The  bracket  form,  moreover, 
of  the  cantilever,  with  its  increased  depth  near  the  piers, 
is  particularly  suited  for  supporting  the  projecting  arms 
during  construction ;  and  it  is  only  necessary,  in  addition, 
to  make  the  ends  of  the  central  portion  capable  of  bear- 
ing the  increased  strains  during  building  out  till  they  are 
joined  in  the  middle. 

Another  form  of  cantilever  bridge,  approximating  to  a 
continuous  girder  bridge  of  varying  depth,  has  been 
adopted  for  the  Kentucky  and  Indiana  Bridge  over 
the  Ohio  at  Louisville,  erected  in  1883-6,  and  for  the 
Poughkeepsie  Bridge,  quite  recently  constructed.  In 
these  bridges,  a  girder  across  a  central  span  was  built  on 
scaffolding,  and  a  projecting  portion  was  built  out  from 
the  ends  of  this  girder  beyond  the  two  piers  supporting 
the  girder,  and  these  projections  formed  cantilevers  for  the 
adjacent  spans,  true  cantilevers  being  built  out  towards 
them  from  the  further  piers.  The  Kentucky  Bridge  has 
two  cantilever  spans,  of  480,  and  483  feet  respectively  be- 
tween the  centres  of  the  piers.  The  Poughkeepsie  Bridge 
has  two  cantilever  spans  on  each  shore  of  523  feet,  and  a 
central  cantilever  span  of  521  feet,  situated  between  two 


Great  Increase  in  Spans  of  Bridges.        1 3 1 

ordinary  girders  of  500  feet  span,  with  projecting  ends 
forming  cantilevers. 

The  cantilever  system,  though  of  recent  adoption  for 
long  span  bridges,  has  been  rapidly  developed  ;  for  the 
Sukkur  Cantilever  Bridge,  crossing  the  Ron  branch  of 
the  river  Indus  at  Sukkur,  with  a  single  span  of  790  feet, 
was  opened  in  June  1889,  and  eclipsed  in  span  all  previous 
bridges  of  rigid  construction.  Within  nine  months,  how- 
ever, of  the  opening  of  the  Sukkur  Bridge,  the  completion 
of  the  Forth  Bridge  put  all  previous  achievements  in 
bridge  building  in  the  shade,  by  exhibiting  a  bridge  with 
two  spans  of  1700  feet,  more  than  double  the  span  of  the 
Sukkur  Bridge,  and  exceeding  the  previously  unrivalled 
Brooklyn  Suspension  Bridge  by  105  feet  in  span. 

In  view  of  this  rapid  advance,  it  may  well  be  wondered 
what  the  future  may  have  in  store  in  regard  to  bridge 
construction.  The  recent  extension  of  the  span  of  rigid 
bridges  is  due  partly  to  the  use  of  steel,  and  partly  to  the 
judicious  adaptation  of  the  cantilever  principle  with  a 
great  depth  over  the  piers.  There  is  no  prospect  at 
present  of  the  discovery  of  any  metal  stronger  than  steel 
and  equally  cheap,  nor  is  there  any  known  untried  prin- 
ciple available  for  still  larger  spans.  With  our  present 
knowledge,  therefore,  the  suspension  system  or  cantilevers 
seem  likely  to  be  resorted  to  for  bridges  of  unusual  span ; 
whilst  continuous  girders  of  varying  depth  appear  capable 
of  being  extended  to  greater  spans  than  girder  bridges 
have  hitherto  attained. 


CHAPTER   VII. 

THE   HAWKESBURY,   ST   LOUIS,   GARABIT,   HOOGHLY, 
BROOKLYN,   FORTH,  AND   TOWER   BRIDGES. 

AMONGST  the  great  number  and  variety  of  bridges  erected 
within  recent  years,  there  is  some  difficulty  in  selecting 
representative  examples  of  the  several  types,  from  dif- 
ferent countries,  for  description,  with  two  exceptions. 
The  Brooklyn  and  Forth  Bridges  stand  out  pre-eminent 
examples  of  the  suspension  and  cantilever  systems  in 
their  grandest  forms.  Of  the  others,  several  similar 
bridges  are  equally  worthy  of  mention  ;  and  those  chosen 
must  be  regarded  merely  as  specimens  of  their  class. 
The  Hawkesbury  Bridge  furnishes  an  instance  of  a  large 
girder  bridge  recently  erected  in  a  British  Colony,  with 
exceptionally  deep  foundations  for  the  piers,  and  where 
the  girders  were  floated  into  position.  The  St  Louis 
and  Garabit  bridges  are  two  of  the  largest  arched 
bridges  in  the  world,  very  different  in  form,  erected,  in 
the  United  States  and  in  France,  by  building  out  from 
the  piers.  (See  page  134.)  The  Hooghly  Bridge,  in 
India,  affords  an  instance  of  a  very  peculiar  form  of 
cantilever  bridge,  in  which  two  of  the  three  spans  were 
put  in  position  by  rolling  out.  The  Tower  Bridge  is  an 
uncommon  example  of  a  bascule  bridge,  or  drawbridge, 
with  a  footway  overhead,  and  is  of  interest  to  Londoners 


BRIDC-ES   WITH  tONO    8PAN9. 


Jl»         BRISSt 


Foundations  of  Hawkesb^lry  Bridge.        135 

as  providing  communication  between  the  two  sides  of  the 
Thames  below  London  Bridge. 

Hawkesbury  Bridge. — A  railway,  formed  to  connect  the 
two  systems  of  railways  of  New  South  Wales,  crosses  the 
Hawkesbury  River  by  means  of  this  bridge.  The  bridge 
has  seven  openings  between  its  piers  placed  about  416  feet 
apart,  centre  to  centre,  on  which  the  steel  girders  rest.  (See 
page  1 34.)  As  the  bottom  of  the  river  consists  of  a  stratum 
of  mud  of  considerable  thickness,  steel  plate  caissons  were 
sunk  at  the  site  of  the  piers,  the  mud  being  removed  from 
the  bottom  of  the  caisson  by  dredging,  and  the  descent  of 
the  weighted  caisson  thereby  accomplished.  The  depth 
of  the  river  varies  from  about  20  feet  to  77  feet ;  the  rise 
of  spring  tides  is  7  feet ;  and  one  of  the  caissons,  adjoining 
the  deepest  channel,  had  to  be  sunk  to  a  depth  of  162  feet 
below  high-water  level  before  reaching  the  firm  stratum  of 
sand,  underlying  the  mud,  on  which  the  piers  have  been 
founded.  The  next  caisson,  in  shallower  water,  and  reach- 
ing the  sand  at  144  feet  below  high-water,  had  to  traverse 
the  maximum  thickness  of  mud  of  about  120  feet ;  and 
owing  to  difficulties  experienced  in  sinking,  though  this 
caisson  was  begun  the  first,  its  sinking  was  completed 
the  last.  The  dredging  was  effected  in  three  circular 
wells,  8  feet  in  diameter,  inside  the  caisson,  and  splayed 
out  at  the  base ;  and  the  caisson  was  weighted  with  con- 
crete placed  between  the  wells  and  the  outer  skin  of  the 
caisson.  As  soon  as  the  caisson  rested  firmly  on  the 
sand,  the  wells  were  filled  with  concrete,  and  the  piers 
built  up  with  masonry  from  near  low-water  level.  As  the 
bridge  crosses  the  main  channel  of  the  estuary  of  the 
Hawkesbury  River  only  seven  miles  away  from  the  sea, 
the  site  is  considerably  exposed,  and  it  was  accordingly 


136  Floating  out  Hawkesbury  Bridge  Girders. 

decided  to  float  the  girders  into  position  on  a  large 
pontoon.  The  pontoon  was  constructed  with  a  staging 
on  it,  so  that,  when  floating  on  the  pontoon,  the  bottom 
of  the  girder  might  be  slightly  higher  than  the  top  of  the 
piers  at  high-water.  After  launching  the  pontoon,  it  was 
stranded  on  a  gridiron  in  a  sheltered  bay  ;  and  the  girders 
of  one  span  were  erected  on  the  staging.  The  pontoon 
was  then  floated  off,  by  closing  its  valves  at  low-water, 
during  favourable  weather ;  and  being  hauled  out  to  the 
site  of  the  bridge,  it  was  moored  between  the  piers  at 
high-water,  and,  as  the  tide  fell,  the  girders  were  deposited 
on  the  piers.  The  same  operations  were  then  repeated 
successively  for  each  of  the  spans.  The  pontoon  on 
one  occasion  was  driven  by  the  current  on  to  some  rocks 
during  low  tide,  and  was  in  danger  of  being  wrecked  with 
its  load  of  girders,  but  was  got  off  at  high-water.  The 
steel  girders  are  of  an  American  pattern,  and  the  con- 
nections are  made  by  bolts ;  they  are  410  feet  long 
between  their  pin  supports,  and  58  feet  high  in  the 
centre.  They  afford  a  clear  headway  of  40  feet  at 
high-water.  The  foundations  of  the  bridge  were  com- 
menced in  1886  ;  and  the  bridge  was  opened  for  traffic 
in  May  1889.  The  bridge  carries  two  lines  of  railway, 
and  has  a  total  length  of  2900  feet ;  and  its  contract  price 
was  £327,000. 

St  Louis  Bridge. — Several  lines  of  railway  converge 
together  on  both  banks  of  the  Mississippi  at  St  Louis, 
necessitating  the  erection  of  a  bridge  across  the  river  at 
this  point,  in  order  to  complete  the  lines  of  communica- 
tion. The  width  of  the  river  is  about  1540  feet  at  a 
narrow  part,  opposite  the  centre  of  the  town,  which  was  the 
site  selected  for  the  bridge.  The  bed  of  the  river  is  com- 


Founding  Piers  of  St  Louis  Bridge,.        137 

posed  of  shifting  sand,  overlying  a  stratum  of  rock  which 
dips  from  32  feet  below  the  water  level  on  the  St  Louis 
side  to  107  feet  on  the  Illinois  side.  As  the  sand  which 
accumulates  in  the  bed  in  the  summer  is  scoured  away  to 
a  considerable  depth  in  flood  time,  when  the  current  in 
the  narrowed  channel  attains  a  velocity  of  8^-  miles  an 
hour,  all  foundations  in  the  river  had  to  be  carried  down 
to  the  solid  rock ;  whilst  the  working  season  only  lasts 
from  August  to  December.  As,  therefore,  it  was  im- 
portant to  reduce  the  number  of  piers  in  the  river  to  a 
minimum,  a  bridge  was  designed  by  Mr  Eads,  crossing 
the  river  by  three  arches,  the  span  of  the  central  opening 
being  520  feet,  and  of  the  two  side  openings  502  feet,  with 
rises  from  the  springing  to  the  crown  of  the  arch  of  47  feet 
and  43f  feet  respectively.  {Seepage  134.)  The  founda- 
tions of  the  St  Louis  abutment,  where  the  rock  was  near  the 
surface,  were  laid  in  the  open  air,  under  the  shelter  of  a 
cofferdam  for  excluding  the  water.  The  foundations,  how- 
ever, of  the  two  river  piers,  and  of  the  Illinois  abutment, 
were  laid  on  the  rock  at  depths  of  76,  102,  and  108  feet 
respectively,  by  means  of  caissons  sunk  by  the  help  of 
compressed  air.  The  sinking  of  the  caisson  for  the  deepest 
pier  occupied  133  days  ;  whilst  the  filling  with  concrete  the 
working  chamber  at  the  bottom  of  the  caisson,  in  which 
the  excavations  had  been  carried  out  during  the  sinking, 
occupied  53  days. 

The  four  arched  ribs  supporting  the  superstructure 
of  the  bridge  across  each  opening  consist  each  of 
two  steel  tubes,  one  above  the  other,  \\  feet  in 
diameter  and  12  feet  apart,  centre  to  centre,  and  braced 
together ;  and  the  tubes,  formed  in  lengths  of  about 
12  feet  bolted  together,  increase  in  thickness  from  the 
centre  to  the  springing.  As  scaffolding  for  erecting  the 


138      Building  out  St  Louis  Bridge  Arches. 

bridge  would  have  impeded  navigation,  and  would  have 
been  difficult  to  maintain  in  shifting  sands,  and  liable  to 
injury  from  floods  and  floating  ice,  the  superstructure  was 
built  out  from  the  piers  and  abutments.  For  a  quarter  of 
the  span  out  from  each  pier,  the  arched  ribs  could  bear 
their  own  weight,  acting  like  a  cantilever.  The  end  of 
each  rib  was  then  supported  by  iron  link  chains,  passing 
over  wooden  towers  erected  on  the  piers,  and  attached  to 
another  similar  projecting  rib  on  the  opposite  side,  or 
anchored  to  the  shore  at  the  abutments,  which  enabled 
some  additional  lengths  of  tubes  to  be  built  out.  This 
additional  portion  was  then  supported  at  the  end  by  link 
chains,  passing  over  a  mast  standing  up  on  the  centre  of 
the  projecting  rib,  and  fastened  at  the  opposite  end  to  the 
springing  plate  against  which  the  arch  abuts  ;  and  by  this 
means  the  portions  of  the  tubes  in  the  centre  of  the  span 
could  be  built  out  and  joined  in  the  centre,  completing  the 
arch.  At  certain  stages  of  this  work  the  chains  above  and 
the  tubes  below,  far  apart  over  the  piers,  and  converging  to 
the  outer  extremity  of  the  projecting  rib,  presented  a  re- 
remarkable  resemblance,  on  a  smaller  scale,  to  the  canti- 
levers of  the  Forth  Bridge  when  in  course  of  erection. 

The  arches  carry  a  double  line  of  railway  below,  between 
the  two  pairs  of  ribs,  and  a  roadway  at  the  top,  54  feet  wide, 
for  carriages  and  foot  passengers.  The  work  was  com- 
menced in  1867,  and  completed  in  1874 ;  and  its  cost  was 
;£ i, 307,000.  This  bridge,  at  the  time  of  its  construction, 
had  the  largest  span  of  any  arched  bridge  in  the  world, 
and  its  foundations  reached  a  greater  depth  than  pre- 
viously attempted  ;  but  it  has  since  been  exceeded  in  span 
by  the  Douro  and  Garabit  arched  bridges  ;  and  a  greater 
depth  of  foundations  was  required  for  the  piers  of  the 
Hawkesbury  Bridge.  Nevertheless,  in  spite  of  the  pro- 


Description  of  the  Garabit  Viaduct.        139 

gress  that  has  been  achieved  in  bridge  construction  during 
the  last  quarter  of  a  century,  the  St  Louis  Bridge  remains 
one  of  the  finest  examples  in  existence  of  an  arched 
bridge,  both  in  respect  of  the  size  of  its  spans,  the 
symmetry  of  its  construction,  the  double  load  it  has  to 
support,  and  its  position  on  a  large  river  with  a  shifting 
bed. 

Garabit  Viaduct. — It  would  be  difficult  to  imagine 
a  structure  combining  more  gracefulness  and  bold- 
ness than  the  beautiful  viaduct  which  has  been  erected 
across  the  precipitous  valley  of  the  river  Truyere,  in  the 
south  of  France,  from  the  designs  of  the  engineer  of  the 
Eiffel  Tower.  (See  page  134.)  This  viaduct,  constructed 
for  the  railway  between  Marvejols  and  Neussargues,  has 
a  total  length  of  1849  feet;  and  the  rail  level  on  the 
viaduct  is  at  a  height  of  401  feet  above  the  water  level 
of  the  river.  The  main  portion  of  the  viaduct  is  con- 
structed of  steel,  and  has  a  length  of  1469  feet,  divided 
into  four  openings  on  one  side,  and  one  on  the  other  side 
of  the  large  arched  span,  each  having  a  width  of  170  to 
182  feet  between  the  centres  of  the  piers.  These  openings 
are  spanned  by  lattice  girders  resting  upon  piers  formed 
of  four  slightly  converging  columns  braced  together  and 
founded  on  a  masonry  base.  The  girders,  carrying  the 
single  line  of  railway,  are  continued  across  the  large  main 
opening ;  and  they  are  supported  by  the  two  high  piers  on 
each  side  of  the  large  opening,  from  the  masonry  base  of 
which  the  arch  springs,  by  two  intermediate  piers  stand- 
ing on  the  arch,  and  by  the  top  of  the  arch  itself  at  the 
centre.  The  trellis  parabolic  arch,  stretching  across  the 
lower  portion  of  the  valley,  has  a  span  of  541  feet,  a  rise 
of  170  feet,  and  a  clear  height  in  the  centre,  above  the 


140      Erection  of  Arch  of  Garabit  Viadiict. 

river  Truyere,  of  356  feet.  The  arch  itself  has  a  depth 
at  the  top  of  33  feet,  and  a  width  of  2Of  feet,  spreading 
out  to  the  springing  to  65!  feet,  with  a  great  corresponding 
reduction  in  depth.  The  girders  supporting  the  roadway, 
and  between  which  the  trains  run,  are  placed  i6J  feet 
apart,  and  have  a  depth  of  17  feet. 

The  design  resembles  the  first  bridge  across  the  Douro 
erected  at  Oporto,  by  M.  Eiffel,  in  1877  ',  an^  the  central 
arch  of  the  Garabit  Viaduct  was  similarly  built  out  from 
the  springing  on  each  side,  like  a  cantilever,  making  use 
of  the  horizontal  roadway  girders,  carried  forward  at  the 
top,  together  with  wire  ropes  suspended  from  a  temporary 
erection  on  the  top  of  each  side  pier  right  across  the  gap. 
The  panels  of  the  arch  were  thus  built  out  by  degrees,  on 
each  side,  till  they  reached  the  centre,  where  they  were 
joined,  forming  a  complete  arch.  Scaffolding  raised  to 
such  a  height  would  have  been  impracticable,  and  there- 
fore the  only  method  of  erecting  the  large  arch  was  by 
building  out  from  each  extremity.  The  viaduct  was  com- 
menced in  1879,  and  the  work  was  completed  in  1884.  The 
crescent-shaped  openwork  arch,  spread  out  laterally  at 
the  springings  to  resist  the  wind  pressure,  rising  to  a 
height  of  about  390  feet  above  the  bottom  of  the  valley, 
and  flanked  on  each  side  by  a  light-looking  viaduct  on 
lofty  tapering  openwork  piers,  forms  a  remarkable  feature 
in  the  picturesque  landscape.  Some  idea  may  perhaps 
be  formed  of  the  scale  of  this  structure  from  the  consider- 
ation that  if  Antwerp  Cathedral  was  placed  at  the  bottom 
of  the  valley,  the  top  of  its  spire  would  be  just  level  with 
the  top  of  the  girder  resting  on  the  summit  of  the  arch  ; 
and  the  arch  would  only  fail  by  10  feet  to  clear  the 
highest  point  of  St  Paul's  Cathedral  if  this  building 
was  standing  underneath  it.  Its  span  exceeds  the  largest 


Description  of  the  Hooghly  Bridge.         141 

spans  of  the  Britannia  Bridge  by  82  feet,  and  has  been  sur- 
passed by  very  few  bridges;  whilst  its  height  is  unrivalled. 

Hooghly  Bridge. — The  river  Hooghly  has  a  width  of 
1 200  feet  at  low-water  at  Hooghly,  being  narrower  there 
than  for  some  distance  above,  and  than  anywhere  lower 
down ;  and  this  site  was  selected  for  a  bridge  to  carry  the 
East  Indian  Railway  across  the  river.  The  main  channel 
lies  near  the  right  bank,  or  Hooghly  side  of  the  river, 
and  is  66  feet  deep,  shoaling  gradually  towards  the 
opposite  bank.  The  erection  of  a  bridge  with  three  equal 
spans  would  have  necessitated  placing  the  river  pier  on 
the  Hooghly  side  in  a  depth  of  40  feet  of  water  at  low 
tide,  where,  owing  to  the  floods  of  the  river  and  the 
tidal  bore,  the  stranding  and  sinking  of  a  large  caisson 
would  have  been  a  hazardous  operation.  Accordingly, 
the  central  span  was  given  an  opening  of  only  95^  feet 
between  the  river  piers,  leaving  clear  openings  of  520  feet 
on  each  side  of  the  river.  (See page  134.)  This  arrange- 
ment, besides  placing  the  Hooghly  pier  in  shallower 
water,  rendered  the  erection  of  the  girders  over  the 
central  span  on  staging  comparatively  easy,  and  provided 
wider  channels  on  each  side  for  the  navigation,  the  larger 
vessels  preferring  the  deep  channel  along  the  right  bank, 
and  the  local  craft  selecting  the  shallow  channel  where 
the  stream  is  not  strong. 

The  wrought-iron  caissons  for  the  river  piers  were 
floated  into  position,  deposited  on  the  river  bed  in  about 
30  feet  of  water,  and  then  sunk  by  dredging  inside,  through 
about  60  feet  of  silt,  down  to  a  stratum  of  solid  clay.  The 
caissons  were  then  filled  with  concrete  below,  and  brick- 
work above,  to  form  the  piers,  being  surmounted  by  steel 
pedestals  to  carry  the  girders.  The  central  girders  were 


142     Erection  of  Girders  of  Hooghly  Bridge. 

then  erected  on  staging  between  the  two  piers ;  and  a 
somewhat  novel  expedient  was  adopted  for  spanning  the 
two  side  openings,  520  feet  in  width.     The  central  girders 
were  built  out  beyond  the  piers,  on  each  side,  by  means  of 
derricks,  so  as  to  form  cantilevers,  projecting  about  113  feet 
beyond  the  piers.     The  shore  girders  on  each  side,  420  feet 
in  length,  were  then  so  placed  as  to  span  the  remainder  of 
the  opening,  resting  at  one  extremity  on  the  shore  abut- 
ment, and  at  the  other  on  the  end  of  the  cantilever.     These 
girders  were  put  in  place  by  rolling  them  out  along  an 
approach  viaduct  of  brickwork,  on  which  they  were  erected, 
and  supporting  their  outer  ends  over  the  river  by  pontoons, 
with  staging  erected  on  them  to  the  required  height,  so 
that  the  ends  of  the  girders  could  be  deposited  on  the 
ends  of  the  cantilevers.     The  erection  of  the  bridge  was, 
accordingly,  partly  effected  by  staging,  and  partly  by  a 
combined  system  of  rolling  out  and  floating  out,  both  of 
which  methods  have  been  often  separately  employed  for 
the  erection  of  bridges.     The  adoption  of  the  cantilevers 
enabled  the  girders  of  the  large  shore  spans  to  be  reduced 
about  one-fifth  in  span,  thus  realising  in  a  conspicuous 
manner  the  practical   reduction  in  span  resulting   from 
continuous  girders.     The  shore  ends  of  the  girders  rest  on 
steel  pins  supported  by  suspended  links,  so  as  to  allow 
of  the  forward  or  backward  movement  required  by   the 
expansion   and    contraction,  resulting   from    changes    in 
temperature,  and  amounting  to  about  3  inches  at  each  end. 
The  cantilever  girders,  30!  feet  apart,  to  provide  for  a 
double  line  of  railway  between  them,  are  52  feet  high  at  the 
centre;  and  the  shore  girders  are  47  feet  high,  being  all  of 
steel,  with  curved  tops  ;  and  the  bridge  affords  a  clear  head- 
way of  53  feet  under  the  girders  at  low- water.     The  works 
were  commenced  in   1883,  and  completed  at  the  end  of 


Peculiar  Form  of  Hooghly  Bridge.         143 

1886;  and  the  cost  of  the  bridge,  including  the  viaducts, 
was  £26 1,000.  Though  the  spans  of  this  bridge  have  been 
very  greatly  exceeded  in  the  Sukkur  Bridge  over  the 
Indus,  the  bridge  possesses  an  interest  from  the  peculiar 
method  in  which  the  cantilever  system  has  been  introduced 
for  modifying  the  position  of  the  piers,  and  facilitating  the 
crossing  of  the  large  openings  ;  whereas  the  Sukkur  Bridge 
presents  too  great  a  resemblance  in  principle  to  the 
gigantic  cantilevers  of  the  Forth  Bridge  to  render  a  separ- 
ate description  expedient.  The  Hooghly  Bridge  is  quite 
a  special  type  in  the  arrangement  of  its  side  spans ;  though 
the  same  kind  of  central  cantilever,  extending  over  two 
piers,  has  been  since  adopted  on  the  Kentucky  and  Indiana, 
and  the  Poughkeepsie  bridges  for  lightening  the  girders 
across  the  adjacent  spans. 

Brooklyn  Bridge. — The  insular  position  of  New  York, 
and  the  difficulties  of  communication  between  the  north 
and  south  of  Manhattan  Island  before  the  construction  of 
the  elevated  railways,  led  to  the  extension  of  Brooklyn 
and  Jersey  City  as  residential  quarters  for  men  engaged 
in  business  in  New  York.  Means  of  access,  accordingly, 
across  the  East,  and  Hudson  rivers  were  obtained  by 
ferries,  pending  a  more  convenient  means  of  communica- 
tion being  achieved.  The  East  River,  however,  is 
considerably  narrower  than  the  Hudson  River,  and 
consequently  the  bridging  of  the  former  was  undertaken 
in  1870,  when  the  erection  of  a  bridge  across  the  latter 
was  considered  impracticable,  though  proposals  have 
recently  been  made  for  accomplishing  this  still  bolder 
feat.  (See  page  120.) 

The    Brooklyn    Bridge,   connecting    New   York    and 
Brooklyn    across  the   East   River,  has  a  total  length  of 


144  Description  of  Brooklyn  Bridge. 

5989  feet,  or  rather  over  a  mile  and  a  furlong.  The 
bridge  has  a  central  span  of  1595^  feet  between  the  two 
towers,  over  which  the  suspension  cables  are  hung ;  two 
side  spans  of  930  feet  each  between  the  towers  and  the 
shore  ;  and  approach  viaducts,  having  lengths  of  1 562^  feet 
on  the  New  York  side,  and  971  feet  on  the  Brooklyn  side 
of  the  river.  (See  illustration.}  The  suspension  towers 
stand  on  two  piers  founded  in  the  river  within  caissons, 
by  the  aid  of  compressed  air,  on  the  solid  rock,  at  depths 
of  78  feet  and  45  feet  below  high-water ;  and  they  rise 
277  feet  above  the  same  level.  There  is  a  clear  headway 
under  the  centre  of  the  bridge  of  135  feet,  and  near  the 
piers  of  118  feet  above  high- water,  thus  affording  ample 
clearance  for  the  masts  of  vessels  passing  underneath. 
There  are  four  suspension  cables,  I5J  inches  in  diameter, 
each  composed  of  5282  galvanised  steel  wires  placed  side 
by  side,  without  any  twist,  as  close  together  as  possible, 
arranged  in  nineteen  strands,  bound  up  with  wire.  This 
method  of  forming  the  cables  was  preferred  to  the  plan 
often  employed  of  twisting  the  wires  together,  as  in  an 
ordinary  rope,  on  account  of  the  greater  tenacity  possessed 
by  the  unbent  wire.  These  cables,  having  a  dip  in  the 
centre  of  the  large  span  of  128  feet,  rest  on  moveable 
saddles  on  the  top  of  the  towers,  to  allow  for  the  slight 
movements  of  the  cables  due  to  changes  of  temperature 
and  load  ;  and  they  are  held  down  at  each  end  by  very 
massive  masonry  anchorages  built  on  shore.  Supple- 
mentary cables  extend  out  like  a  fan  on  each  side  of  the 
towers,  and  both  assist  in  supporting  the  two  shore  spans, 
and  the  portion  of  the  long  span  roadway  nearest  the 
towers,  and  brace  the  roadway  to  reduce  its  deflection 
under  heavy  loads.  After  the  foundations  of  the  piers 
had  been  laid,  the  piers  built,  and  the  towers  erected,  the 


Erection,  Width  and  Cost  of  Brooklyn  Bridge.    145 

first  travelling  wire  rope  was  passed  over  one  of  the  towers 
in  1876,  conveyed  by  a  steamboat  across  the  river,  and 
after  being  passed  over  the  other  tower,  the  rope,  which 
was  allowed  to  drop  to  the  bottom  of  the  river  whilst  its 
end  was  carried  across,  was  drawn  tight  at  a  moment  when 
the  channel  was  free  from  shipping;  and  the  first  step 
towards  connecting  Brooklyn  with  New  York  was  thus 
accomplished.  A  second  travelling  rope  was  similarly 
established  and  connected  with  the  first ;  and  by  aid  of 
this  continuous  wire  rope,  a  temporary  suspended  platform 
was  erected,  on  which  the  strands  of  the  cables  were  then 
gradually  put  in  place  ;  and,  lastly,  the  suspending  ropes, 
and  the  platform  of  the  bridge  were  fixed. 

The  bridge  has  a  width  of  85  feet,  separated  into 
five  divisions;  the  centre  one.  15^  feet  wide,  and  raised 
12  feet  above  the  rest  of  the  bridge,  forms  a  footway, 
on  each  side  of  which  there  is  a  line  of  rails  for  a 
rope  railway,  worked  by  a  stationary  engine  on  the 
Brooklyn  side;  and  on  the  outside  there  is  a  roadway 
for  carnages  and  carts,  19  feet  wide,  on  each  side.  The 
bridge,  therefore,  carries  two  roadways,  two  lines  of 
railway,  and  a  footway.  The  bridge  was  opened  in 
1883  ;  and  it  cost  about  £3, 100,000,  about  three  times 
the  original  estimate. 

For  seven  years  the  Brooklyn  Bridge  remained  the 
bridge  with  by  far  the  largest  span  in  the  world  ;  but  the 
Forth  Bridge  deprived  it  of  this  pre-eminence,  on  its  com- 
pletion in  1890,  by  having  two  spans  exceeding  the  large 
span  of  the  Brooklyn  Bridge  by  1 1 5  feet.  The  Brooklyn 
Bridge,  like  most  suspension  bridges,  is  a  graceful  struc- 
ture ;  and  it  has  rendered  a  very  important  service  to  both 
Brooklyn  and  New  York  by  providing  an  easy  means  of 
communication  between  the  two  towns.  In  the  proposed 

K 


146    Schemes  for  crossing  the  Firth  of  Forth. 

bridging  of  the  Hudson  River  by  a  monster  suspension 
bridge,  the  Brooklyn  Bridge  is  threatened  by  a  formidable 
rival,  on  the  opposite  side  of  New  York,  which,  if  erected 
as  designed,  would  outstrip  the  large  Brooklyn  span  by 
as  great  a  proportion  as  the  Brooklyn  Bridge  surpassed 
any  of  its  predecessors. 

The  Forth  Bridge. — The  railways  from  England  con- 
verging to  Edinburgh  were  prevented  from  following 
a  direct  route  to  Perth,  Dundee,  Aberdeen,  and  other 
large  towns  on  the  east  coast  of  Scotland,  by  the  Firth  of 
Forth,  so  that  the  traffic  had  either  to  make  a  long 
detour  by  Stirling,  or  to  be  conveyed  across  the  Firth  of 
Forth  by  ferry.  The  Firth,  which  is  very  broad  opposite 
Leith,  the  port  of  Edinburgh,  is  contracted  to  about  a  mile 
in  width  at  Inverkeithing,  where  a  ferry  had  been  long 
established  between  North  and  South  Queensferry ;  and, 
moreover,  the  small  island  of  Inchgarvie,  situated  in  mid- 
channel  at  this  narrowed  part,  divides  the  channel  into 
two  equal  portions.  The  idea  of  bridging  the  Forth  at 
this  point  is  said  to  have  been  first  put  forward  about 
150  years  ago,  and  in  1805  a  double  tunnel  was  proposed 
for  effecting  the  crossing;  whilst  in  1818  a  design  for  a 
suspension  bridge  over  the  site  of  the  present  bridge, 
and  with  very  similar  spans,  was  published.  Nothing 
further  was  done  in  the  matter  till  the  erection  of  a  rail- 
way bridge,  higher  up  the  Firth,  with  spans  of  510  feet, 
was  authorised  in  1865,  which  project  was  subsequently 
abandoned.  In  1873  a  company  was  formed  and 
authority  obtained  for  the  erection  of  a  steel  suspension 
bridge  at  Queensferry,  with  two  spans  of  1600  feet,  a 
clear  headway  of  150  feet,  and  towers,  550  feet  above 
high-water,  on  Inchgarvie  Island  and  the  two  shores,  for 


Site  and  Form  of  Forth  Bridge.  147 

supporting  the  chains.  This  bridge  had  been  actually 
commenced,  when  the  overthrow,  by  a  gale  in  1879,  of  the 
large  spans  of  theTay  Bridge,  erected  by  the  designer  of 
the  Forth  Suspension  Bridge,  led  to  a  reconsideration 
of  the  plans.  Eventually,  after  a  comprehensive  inquiry 
into  the  original  design,  other  forms  of  stiffened  suspen- 
sion bridges,  the  cantilever  system,  and  a  tunnel,  a  modified 
design,  on  the  cantilever  principle,  proposed  by  Messrs 
Fowler  and  Baker,  was  approved  in  1881,  and  has  now 
been  carried  out.  The  land  rises  rapidly  from  each 
shore  at  Queensferry,  and  the  site  was  therefore  specially 
suitable  for  the  approaches  to  a  bridge  which  had  to 
be  constructed  at  a  high  level  to  afford  adequate  head- 
way for  vessels  to  pass  underneath.  For  the  same 
reason,  combined  with  the  great  depth  of  water,  ex- 
ceeding 200  feet,  in  the  two  channels  between  Inch- 
garvie  Island  and  the  shore,  the  site  was  not  favourable 
for  a  subaqueous  tunnel. 

The  bridge,  as  erected,  consists  of  two  approach 
viaducts ;  three  double  cantilevers,  resting  on  two  piers 
near  the  shore  and  on  a  central  pier  on  the  island ;  and 
two  pairs  of  ordinary  girders,  spanning  the  intervals 
between  the  ends  of  the  central  and  side  cantilevers  over 
the  two  deep  channels.  {See  illustration.)  The  approach 
viaducts  are  formed  by  girders,  from  1 68  to  179  feet  in 
length,  resting  upon  masonry  piers,  spanning  five  openings 
on  the  north  side,  and  ten  on  the  south  side,  together 
with  masonry  arches  at  the  extremities.  The  cantilevers 
are  symmetrical  steel  structures,  rising  361  feet  above 
high-water,  composed  of  a  central  portion  over  the  piers, 
from  which  two  cantilever  arms  extend  out  on  each  side, 
680  feet  in  length,  and  tapering  to  their  extremities  both 
vertically  and  horizontally.  The  central  portions  of  the 


148  Cantilevers  of  Forth  Bridge. 

cantilevers  consist  of  four  vertical  columns,  each  resting 
upon  a  circular  granite  pier,  which  are  120  feet  apart  at 
the  bottom,  and  33  feet  apart  at  the  top  across  the  bridge. 
Longitudinally,  the  columns  of  the  two  side  piers  are 
145  feet  apart  from  bottom  to  top ;  whilst  the  columns  of 
the  central  pier  on  Inchgarvie  Island  are  260  feet  apart. 
This  considerably  greater  width  has  been  given  to  the 
central  pier  to  enable  it  to  resist  the  leverage  produced  when 
one  end  of  its  cantilever  arm  is  fully  loaded  by  two  trains 
meeting  on  one  of  the  central  girders,  and  the  other  conse- 
quently unloaded,  which  leverage  cannot,  in  the  case  of  the 
central  cantilever,  be  provided  against  by  a  counterpoise 
weight,  such  as  is  placed  at  the  shore  ends  of  the  other 
two  cantilevers  which  are  encased  in,  and  rest  on  the 
shore  abutments.  The  vertical  columns  are  connected  at 
the  top  and  bottom,  and  strongly  braced  together  hori- 
zontally and  vertically.  The  cantilever  arms  are  the  same 
in  all  the  cantilevers,  except  that  the  fixed  counterpoised 
shore  arms  are  somewhat  heavier  in  construction.  They  are 
composed  of  two  circular  curved  steel  tubes  at  the  bottom 
in  compression,  and  two  flanged  lattice  steel  ties  at  the  top 
in  tension,  braced  together  horizontally  and  vertically  ;  and 
the  top  ties  and  the  bottom  tubes  converge  vertically  from 
330  feet  at  the  piers  to  34  feet  at  the  extremities,  and  from 
1 20  feet  at  the  bottom  and  33  feet  at  the  top  at  the  piers, 
to  32  feet  and  22  feet  respectively  at  the  extremities 
horizontally.  The  cantilevers,  accordingly,  form  very 
strong  balanced  double  brackets,  with  such  a  great  depth 
over  the  piers  and  so  strongly  braced  as  to  be  able  to 
support  a  considerable  load  on  their  extremities.  Ac- 
cordingly, the  ends  of  the  cantilevers,  stretching  over  the 
channels,  serve  as  piers  for  girders  of  350  feet  span,  com- 
pleting the  communication  between  the  cantilevers  over  the 


Description  of  Forth  Bridge.  149 

two  channels;  and  the  cantilevers  and  girders  together 
compose  a  bridge  affording  two  clear  openings  of  1700  feet 
between  the  piers.  The  road  for  the  double  line  of  way  is 
supported  by  cross  girders  between  the  central  girders ;  and 
longitudinal  roadway  girders,  resting  on  uprights  borne 
by  the  cantilevers,  carry  the  railway,  with  a  uniform 
width  of  road  and  at  a  uniform  level,  between  the  canti- 
levers. The  widening  out  of  the  cantilevers  vertically 
towards  the  piers  is  required  to  enable  them  to  resist  the 
strains  involved  in  so  great  a  span  as  1700  feet;  and  the 
horizontal  increase  in  width  affords  stability  against  wind 
pressure,  increasing  in  proportion  to  the  surface  exposed, 
which,  in  the  cantilever  system,  is  greatest  at  the  piers 
and  least  in  the  centre  of  the  span.  The  shore  ends  of  the 
side  cantilevers,  besides  being  counterpoised  sufficiently  to 
counterbalance  the  train  load  on  their  outer  extremities, 
are  also  provided  with  an  adequate  additional  weight  to 
counterbalance  half  the  weight  of  the  central  girder. 

The  total  length  of  the  bridge,  together  with  the 
approach  viaducts,  is  8098  feet,  or  a  little  over  a  mile  and 
a  half ;  the  length  of  the  cantilever  portion  is  5349  feet,  or 
rather  more  than  a  mile ;  the  total  length  of  the  central 
cantilever  is  1620  feet,  and  of  the  two  side  cantilevers, 
1514!  feet;  and  the  clear  headway  under  the  central 
girders,  at  ^high-water,  is  1 50  feet.  The  actual  bridge, 
exclusive  of  the  approach  viaducts,  consists  of  three 
piers,  two  clear  spans  of  1700  feet  over  the  two 
channels  on  each  side  of  the  island,  and  two  openings 
at  the  sides  of  about  680  feet  each,  spanned  by  the 
counterbalancing  arms  of  the  shore  cantilevers,  the 
northern  one  stretching  over  the  land,  and  the  southern 
one  over  a  shallow  foreshore  bordering  the  southern 
channel.  The  central  girders  are  attached  at  one 


1 50  Foundations  of  the  Piers  of  Forth  Bridge. 

end  to  the  adjacent  side  cantilevers,  but  are  left  free 
at  the  other  end  on  the  central  cantilever,  to  allow 
for  the  movements  resulting  from  expansion  and  con- 
traction. 

The  works  were  commenced  at  the  beginning  of 
1883  ;  and  preparations  were  made  for  founding  the  twelve 
piers,  in  groups  of  four,  on  the  island  and  each  bank,  on 
which  the  vertical  columns  of  the  cantilevers  rest.  The 
two  northern  piers  on  the  Fife  shore  were  built  on  land 
without  difficulty,  and  rested  on  a  rock  foundation  ;  and  the 
two  other  piers  on  the  Fife  shore,  and  the  two  northern 
piers  on  the  island,  were  built  under  the  shelter  of  water- 
tight casings,  or  cofferdams,  enclosing  each  site.  The  two 
southern  piers,  however,  on  the  island,  and  the  four 
southern  or  Queensferry  piers,  had  to  be  constructed  by 
the  aid  of  caissons,  with  compressed  air,  which  were  sunk 
gradually  till  a  solid  level  foundation  was  reached,  when 
the  working  chamber  and  caisson  were  rilled  with  con- 
crete to  form  the  foundation  for  the  granite  pier.  The 
chief  difficulty  experienced  in  sinking  the  two  Inchgarvie 
caissons  resulted  from  the  dip  of  the  rock,  so  that  whilst 
one  portion  of  the  caisson  rested  upon  firm  rock,  the 
other  side,  being  unsupported,  was  liable  to  sink  to 
a  lower  level  and  tilt  the  caisson,  which  had,  accord- 
ingly, to  be  propped  up  with  concrete  piers  and  sand 
bags  to  keep  it  level,  till  the  rock  on  the  higher  side 
could  be  cut  away.  The  Queensferry  caissons  were 
sunk  through  from  33  to  45  feet  of  silt,  boulder  clay, 
and  hard  ground,  to  a  solid  foundation,  the  deepest 
foundation  being  89  feet,  and  the  shallowest  71  feet 
below  high-water.  Comparatively  little  excavation  had 
to  be  effected  in  sinking  the  Inchgarvie  caissons,  beyond 
levelling  the  rock ;  so  that,  though  owing  to  the  greater 


Erection,  and  Cost  of  Forth  Bridge.         1 5 1 

depth  of  water  at  this  site  than  at  the  Queensferry 
piers,  the  foundations  were  64  and  72  feet  below  high- 
water,  the  launching,  placing,  and  sinking  the  caissons 
only  occupied  about  four  months.  Three  of  the  Queens- 
ferry  caissons  required  from  five  to  six  months  for  the 
same  operations ;  and,  owing  to  the  accidental  ground- 
ing, tilting  up,  and  submergence  of  the  fourth  caisson, 
fourteen  months  elapsed  between  its  launching  and  final 
sinking  to  its  full  depth. 

As  soon  as  the  piers  were  completed,  the  central  portions 
of  the  cantilevers  were  erected,  and  the  arms  were  then  built 
out  in  both  directions  without  staging ;  and  the  central 
girders  were  also  built  out  from  each  end  of  the  ad- 
jacent cantilever  arms,  till  they  met  in  the  middle  and 
were  finally  connected.  The  work  of  erection  of  such 
long  heavy  pieces  to  a  great  height,  and  to  great  distances 
from  the  piers,  without  any  fixed  staging,  involved  very 
considerable  difficulties.  Special  machinery  and  special 
plant  were  required  for  carrying  out,  adjusting,  and  con- 
necting the  various  parts;  the  slanting  positions  of  the 
columns  and  struts  caused  them  to  bend  under  their  own 
weight ;  a  high  wind  forced  the  long  detached  portions  out 
of  their  proper  lines  ;  and  even  the  heat  of  the  sun  led  to 
temporary  deflections ;  all  which  deviations  had  to  be  re- 
adjusted before  the  various  parts  of  the  structure  could  be 
joined  together.  The  bridge  was  opened  in  March  1890, 
about  seven  years  after  the  commencement  of  the  works. 
The  weight  of  steel  used  in  the  cantilever  portion  of  the 
bridge  was  about  51,000  tons.  The  total  cost  of  the 
works  in  connection  with  the  bridge  has  been  about 
.£3,250,000,  which  is  about  double  the  original  parlia- 
mentary estimate. 

The  bridge  is  devoid  of  any  extraneous  architectural 


152          Aspect  and  Size  of  Forth  Bridge, 

adornments,  and  is  a  model  of  simplicity  and  utility  com- 
bined. It  has  been  described  by  some  persons  as  ugly ; 
and  when  looked  at  from  the  shore  ends,  the  convergence 
of  its  sides  gives  it  a  peculiar  appearance.  When  viewed, 
however,  from  the  water,  the  grandeur  of  its  proportions 
is  more  thoroughly  realised ;  and  the  massiveness  of  its 
columns  and  struts  is  lightened  by  the  apparent  slender 
network  of  cross  bracing,  whilst  the  convergence  of  its 
sides  is  not  seen.  The  large  sizes  of  its  several  parts 
are  best  observed  from  the  footways,  running  along  each 
side  of  the  railway  across  the  bridge,  from  whence  also 
the  great  height  and  width  of  the  cantilevers  over  the 
piers  can  be  most  advantageously  perceived,  at  an 
elevation  of  about  half  their  height.  It  is  difficult 
from  any  other  point  of  view  to  grasp  the  real  mag- 
nitude of  the  structure ;  for  the  central  girders,  of 
380  feet  span,  which  in  any  other  bridge  would  be 
regarded  as  considerable,  appear  quite  diminutive  in 
comparison  to  the  gigantic  cantilevers  on  each  side  of 
them. 

The  two  cantilever  arms  alone  of  one  span  of  the  Forth 
Bridge,  exclusive  of  the  central  girder,  are  250  feet  longer 
than  the  height  of  the  Eiffel  Tower ;  and  the  cantilevers 
rise  over  the  piers,  above  high-water,  to  within  5  feet  of 
the  height  of  St  Paul's.  Each  of  the  large  spans  is  about 
200  feet  longer  than  the  total  length  of  the  Britannia 
Bridge,  with  its  four  spans,  and  longer  than  Waterloo 
Bridge,  with  its  eight  arches  including  its  shore  spans ; 
and  one  span  alone  would  stretch  across  the  Thames  at 
Woolwich,  or  the  Mississippi  at  St  Louis.  The  two  spans 
of  the  Forth  Bridge  would  traverse  the  East  River  at  the 
site  of  the  Brooklyn  Bridge  ;  and  the  cantilevers  are  about 
85  feet  higher  above  the  water  than  the  towers  of  the 


Forth  and  Brooklyn  Bridges  compared.      1 53 

Brooklyn  Bridge,  though  their  height  is  very  much 
masked  by  their  great  proportionate  length,  the  length  of 
the  central  cantilever  being  four  and  a  half  times  its  height. 
The  Forth  Bridge  has  not  the  light  appearance  of  the 
Brooklyn  Bridge,  in  which  particular  suspension  bridges 
excel,  but  it  possesses  greater  rigidity ;  and  though  it  has 
not  nearly  the  width  of  roadway  of  the  Brooklyn  Bridge, 
it  exceeds  it  by  105  feet  in  span.  The  two  large  spans  of 
the  Forth  Bridge  correspond  approximately  in  length  to 
the  large  span  and  two  shore  spans  at  Brooklyn ;  but  the 
counterbalancing  cantilever  spans,  with  the  approaches,  at 
the  Forth  Bridge  are  longer  than  the  Brooklyn  Bridge 
approaches ;  so  that  the  Forth  Bridge,  altogether,  is 
about  3  furlongs  longer  than  the  Brooklyn  Bridge, 
whilst  it  provides  less  accommodation  in  width.  These 
two  bridges,  far  excelling  all  others  in  span,  though  not 
really  comparable,  happen  to  have  cost  very  nearly 
the  same  amount,  which  in  both  cases  largely  exceeded 
the  original  estimates ;  and  this  result  may  lead  to 
hesitation  in  undertaking  the  construction  of  long  span 
bridges.  The  Forth  Bridge  has  proved  very  firm  under 
heavy  loads,  and  has  already  attracted  a  large  quantity 
of  traffic.  Its  successful  completion  has  demonstrated  the 
advantages  of  the  cantilever  system  for  large  spans. 

The  Sukkur  Bridge  resembles  the  Forth  Bridge  in 
having  a  central  girder,  with  a  span  of  200  feet,  supported 
at  the  ends  of  two  cantilever  arms,  each  310  feet  long; 
but  the  cantilevers  of  the  Sukkur  Bridge  are  less  sym- 
metrical, and  their  parts  are  more  massed  together  than 
in  the  Forth  Bridge. 

The  Tower  Bridge. — The  bridge  which,  after  long  dis- 
cussion of  various  schemes,  was  designed  for  providing 


154         Object  and  Form  of  Tower  Bridge. 

a  connection  between  both  banks  of  the  Thames  below 
London  Bridge,  is  still  in  course  of  construction  just  below 
the  Tower.  The  most  uncertain  portion,  however,  of  the 
work,  namely,  the  foundations  of  the  river  piers,  has  already 
been  accomplished,  so  that  only  the  erection  of  the  towers 
on  the  piers,  and  the  superstructure  of  the  bridge  remain 
to  be  carried  out;  and  it  is  anticipated  that  the  bridge 
will  be  finished  at  the  end  of  1892.  The  bridge  is  not  re- 
markable for  any  specially  large  span ;  but  it  possesses 
an  interest  from  the  peculiarity  of  its  design,  which  dis- 
tinguishes it  from  all  bridges  hitherto  erected  over  the 
Thames,  and  also  as  solving  the  problem  of  providing 
a  convenient  roadway  across  the  river  below  London 
Bridge  without  unduly  impeding  navigation.  Schemes 
have  been  proposed  for  a  tunnel  under  the  bed  of  the  river, 
or  a  high-level  bridge  over  the  river ;  but  the  long,  steep 
approaches  required  in  either  case  on  each  side,  in  a 
densely  crowded  and  valuable  part  of  the  metropolis,  have 
proved  an  insuperable  obstacle.  The  present  design 
obviates  that  difficulty  by  providing  an  opening  central 
span  for  vessels,  and  thus  enabling  the  approaches  on  each 
side  to  reach  the  bridge  from  the  main  thoroughfares  with 
less  rise  than  at  London  Bridge.  (See  illustration.) 

The  distance  between  the  two  abutments  of  the  bridge, 
on  each  side  of  the  river,  is  880  feet,  divided  into  three 
openings  by  two  river  piers,  70  feet  in  width,  the  two 
side  openings  being  270  feet  in  width,  and  the  central 
opening  200  feet.  The  roadways  of  the  two  side  open- 
ings are  to  be  suspended  from  chains  hanging  from  the 
high  towers  on  the  river  piers  to  the  lower  towers  on  the 
abutments.  The  central  opening  is  to  be  spanned  by  a 
double  bascule  or  drawbridge,  the  two  halves  being  pivoted 
in  the  piers,  and  when  down  forming  a  flat  arch  across  the 


It 


Arrangements  of  Tower  Bridge.  155 

opening,  with  a  headway  in  the  centre  of  29^  feet  above 
high-water.  These  two  halves  are  counterbalanced  at 
their  -tail  ends,  extending  inside  the  piers,  and  can  be 
raised  by  machinery  to  a  vertical  position  against  each 
tower,  so  as  to  be  quite  clear  of  the  opening,  the  tail  ends 
revolving  in  segmental  recesses  provided  in  the  piers,  and 
the  roadway  portions  going  partially  into  vertical  recesses 
in  the  faces  of  the  towers  on  the  piers.  When  the  bascule 
bridge  is  open,  a  clear  headway  of  139!  feet  will  be 
afforded  between  high-water  and  a  light  fixed  upper  road- 
way for  foot  passengers,  resting  on  the  upper  part  of  the 
river  towers,  and  spanning  the  central  opening  between 
the  towers.  Access  to  this  upper  roadway  is  provided  by 
staircases  and  hydraulic  lifts  inside  the  towers ;  so  that 
foot  passengers  will  always  be  able  to  cross  the  river, 
even  when  the  bridge  is  closed  to  vehicles  for  the 
passage  of  vessels.  The  width  between  the  parapets 
will  be  50  feet  in  the  opening  span,  and  60  feet  along 
the  approaches  and  side  spans.  The  approaches  have 
been  built  on  brick  arches ;  and  the  gradient  nowhere 
exceeds  I  in  40.  Hydraulic  power  will  be  supplied 
by  engines  on  the  Surrey  side ;  and  hydraulic  ac- 
cumulators, which  are  weighted  cylinders  for  main- 
taining the  water  pressure,  are  to  be  placed  in  the  piers, 
so  as  to  store  up  power  for  working  the  machinery  for 
opening  the  bridge  and  raising  the  passenger  lifts.  Most 
of  the  metal  work  in  the  bridge  and  towers  is  to  be 
steel ;  the  weight  of  each  leaf  of  the  bascule  bridge, 
with  its  counterpoise  weight,  will  be  950  tons ;  and 
the  weight  of  iron  and  steel  in  the  bridge  will  amount 
to  15,000  tons. 

The  foundations  for  the  river  piers  were  laid  within 
wrought-iron  caissons,  sunk  to  a  depth  of  27  feet  below 


156    Construction  and  Cost  of  Tower  Bridge. 

the  river  bed,  and  60  feet  below  high-water ;  but  the 
foundations  of  the  two  piers  could  not  be  carried  on 
simultaneously,  as  the  amount  of  staging  allowed  in  the 
channel  at  one  time  was  restricted  on  behalf  of  the 
navigation,  so  that  the  progress  of  the  work  was  thereby 
delayed.  Parliamentary  sanction  for  the  construction 
of  this  bridge  was  obtained  in  1885  ;  the  foundation 
stone  was  laid  in  1886;  and  progress  is  now  being  made 
with  the  towers  and  superstructure.  The  length  of  the 
bridge  and  abutments  is  940  feet,  and  of  the  approaches 
1700  feet,  making  a  total  length  of  2640  feet;  and  the 
estimated  cost  of  the  work  is  £7 50,000.  Wooden  bascule 
bridges  are  very  common  in  Holland,  especially  in  Am- 
sterdam, over  the  numerous  canals  intersecting  that  city ; 
but  they  have  been  rarely  employed  for  large  spans. 
Bridges  turning  horizontally  on  a  pivot,  known  as  swing 
bridges,  are  much  more  common,  but  would  have  been 
unsuited  for  the  centre  of  a  crowded  river,  owing  to  the 
space  occupied  by  them  when  open. 

The  Tower  Bridge,  with  its  suspended  shore  spans,  its 
high  river  towers,  its  high-level  footway,  and  its  bascule 
bridge,  will  have  features  of  novelty  and  architectural 
merits  not  always  possessed  by  engineering  works,  and 
will  also  be  a  great  advantage  in  facilitating  communica- 
tion below  London  Bridge. 

Proposed  Channel  Bridge. — The  success  of  any  large 
undertaking  generally  leads  to  proposals  for  the  construc- 
tion of  works  of  still  greater  magnitude.  It  is  proposed, 
as  previously  mentioned,  to  follow  up  the  Brooklyn  Bridge 
by  the  erection  of  a  much  larger  suspension  bridge  across 
the  Hudson  River  ;  and  the  completion  of  the  Forth  Bridge 
has  imparted  fresh  vigour  to  schemes  for  bridging  the 


Proposed  Channel  Bridge.  157 

English  Channel,  in  place  of  the  Channel  Tunnel.  The 
promoters  of  the  latest  design  naturally  adopt  the  canti- 
lever system,  selecting  the  principle  of  the  Kentucky  and 
Indiana  Bridge,  across  the  Ohio,  of  girders  supported  on 
two  piers, and  projecting  beyond  them  as  cantilevers  on  each 
side,  supporting  smaller  central  girders  at  their  extremities 
over  the  intermediate  or  cantilever  spans.  The  bridge, 
traversing  the  Channel  at  the  Straits  of  Dover,  would  have 
a  length  of  24  miles,  nearly  twelve  times  the  length  of  the 
Tay  Bridge.  It  is  to  be  borne  on  120  piers,  the  piers  in 
the  main  deep  channel  attaining  a  depth  of  180  feet  below 
high-water,  and  supporting  the  girders  at  a  height  of 
1 80  feet  above  high- water,  to  afford  that  clear  headway 
for  vessels  navigating  the  Channel.  The  large  cantilever 
spans  in  mid-channel  are  to  have  openings  of  1640  feet ; 
whilst  the  distance  between  the  piers  of  the  intermediate 
supporting  girders  is  to  be  984  feet.  Other  spans,  of  from 
328  to  830  feet,  are  to  be  formed  in  the  shallower  and  less 
frequented  parts  of  the  Channel.  The  estimated  amount 
of  metal  required  is  1,000,000  tons,  or  about  forty  times 
the  quantity  used  in  the  Forth  Bridge  ;  and  the  estimated 
cost  is  about  £34,000,000.  The  height  of  the  largest 
girders  is  to  be  213  feet,  so  that  the  total  height  of  the 
highest  portion  of  the  structure  would  be  about  570  feet 
above  the  sea  bottom,  or  40  feet  higher  than  the  top  of 
the  spires  of  Cologne  Cathedral,  the  highest  building  in 
the  world  with  the  exception  of  the  Eiffel  Tower.  A 
bridge  across  the  Channel  is  not  dependent  upon  the  con- 
tinuity of  the  chalk  stratum  like  a  tunnel,  and  passengers 
on  the  Channel  Bridge  in  a  stormy  night  would  be  in  no 
need  of  ventilation  ;  but  in  other  respects  a  bridge  would 
involve  much  greater  difficulties  in  construction,  in  the 
open  sea  at  such  a  depth,  than  a  tunnel  through  chalk. 


158        Channel  Bridge  or  Channel  Tunnel. 

Moreover,  the  much  greater  cost  of  a  bridge,  and  the 
danger  presented  to  shipping  in  fogs  or  storms  by  a  num- 
ber of  piers  in  mid-channel,  appear  to  render  a  Channel 
bridge  inexpedient,  unless  a  tunnel  should  prove  to  be 
impracticable. 


CHAPTER    VIII. 

SUBMARINE    MINING   AND   BLASTING. 

EXCAVATION  under  water,  known  by  the  general  term  of 
dredging  when  soft  material  has  to  be  removed,  is  gener- 
ally cheaper  than  excavation  on  land,  owing  to  the  large 
floating  dredging  machines  that  can  be  employed,  and 
readily  moved  about,  and  owing  to  the  economy  with  which 
the  carriage  of  the  lifted  material  to  a  suitable  place  of 
deposit  can  be  effected  by  water.  When,  however,  rock 
impedes  the  widening  or  deepening  of  a  navigable  channel, 
its  removal  is  attended  with  difficulty,  and  involves  a  con- 
siderable expense.  Blasting  on  land  is  a  slow  and  some- 
what costly  operation  ;  but  blasting  under  water,  where  the 
boring  of  the  holes  has  to  be  effected  in  an  unseen  rock, 
and  the  blasting  charges  have  to  be  inserted  and  fired  under 
water,  is  much  more  tedious  and  expensive.  As  the  exe- 
cution of  such  works  depends  in  great  measure  upon 
questions  of  cost,  a  large  rocky  shoal  presents  a  very 
serious  impediment  to  the  improvement  of  a  channel. 
Rocks  under  water  have,  however,  been  removed  when 
not  large  in  extent,  and  when  they  have  presented  a 
serious  danger  to  shipping,  as  for  instance  in  Holyhead 
and  Alderney  harbours.  Rocky  shoals,  also,  extending 
across  river  channels,  and  limiting  the  improvement  in 


160  Removal  of  Rock  under  Water. 

depth  that  can  be  obtained  by  dredging,  have  been  lowered 
in  recent  years  by  drilling  from  special  rafts,  the  explosive 
being  deposited  in  the  holes  either  through  tubes  or  by 
divers,  as  in  the  Tees,  the  Yarra  River  in  Australia,  and 
elsewhere.  Dynamite  and  nitro-glycerine  have  been  em- 
ployed for  the  blasting,  being  fired  by  fuses  or  electricity, 
with  the  help  of  a  detonator  such  as  fulminate  of  mercury, 
which,  by  causing  a  concussion,  ensures  the  complete- 
ness of  the  explosion.  Drilling  machines,  also,  worked 
by  compressed  air,  have  been  used  for  drilling  the 
blasting  holes  from  a  barge.  Sometimes  dynamite  has 
been  employed  for  shattering  subaqueous  rocks,  by  being 
exploded  when  simply  in  contact  with  the  rock  ;  but  a 
good  deal  of  the  power  of  the  explosive  is  wasted  by 
this  arrangement,  and  it  is  not  advantageous  when  the 
rock  is  massive.  These  are  the  ordinary  methods  of 
removing  rock  under  water ;  but  there  are  three  other 
systems  for  effecting  this  object,  one  of  which  has 
enabled  a  gigantic  operation  for  deepening  a  channel  to 
be  accomplished. 

Compressed  Air  Diving-BelL — A  peculiar  form  of  float- 
ing diving-bell,  into  which  compressed  air  can  be  intro- 
duced, has  been  employed  for  facilitating  the  removal  of 
rocks  in  Brest  and  Cherbourg  harbours.  The  lower 
portion  of  the  apparatus  consists  of  a  large  plate-iron 
caisson,  33  feet  long,  26\  feet  wide,  and  23  feet  high, 
which  is  divided  into  two  parts  by  a  watertight  horizontal 
diaphragm,  about  6J  feet  above  the  bottom  which  is  left 
open.  The  lower  division  forms  the  working  chamber, 
which  can  be  filled  with  compressed  air  by  a  pipe  leading 
from  air  compressors  on  shore.  The  upper  division  makes 
the  apparatus  float  when  full  of  air,  or  sinks  it  when  water 


Compressed  A  ir  Diving  Bell.  1 6 1 

is  admitted.  The  sides  are  carried  up,  somewhat  converg- 
ing, above  the  caisson  to  a  sufficient  height  to  place  the 
platform  at  the  top  above  high-water  when  the  caisson  is 
sunk  in  position.  A  staircase,  in  a  large  central  shaft, 
leads  from  the  top  platform  to  the  air-locks  on  the  roof  of 
the  working  chamber  ;  whilst  two  smaller  shafts,  on  each 
side,  serve  for  the  removal  of  the  displaced  rock.  The 
caisson  is  ballasted  near  the  bottom  with  masonry 
and  pig-iron  to  make  it  float  upright.  The  caisson 
is  floated  out  to  the  required  spot,  and  sunk  by  ad- 
mitting water  into  the  air  chamber  above  the  working 
chamber.  The  men  then  enter  the  working  chamber, 
lit  by  electric  light,  from  which  the  water  is  excluded 
by  compressed  air ;  and  when  the  holes  have  been  bored 
in  the  rock  and  charged,  the  men  retire  into  the  air- 
locks for  the  blast.  The  men  can  thus  mine  and  blast 
the  submarine  rocks  as  if  they  were  out  of  water ;  and 
at  the  termination  of  the  work,  compressed  air  being  let 
into  the  air  chamber,  forces  out  the  water,  and  floats  the 
apparatus. 

Rock-breaking  Rams. — Another  system  of  dealing  with 
rock  under  water  is  by  first  breaking  the  rock  up  by  a 
succession  of  blows,  delivered  by  a  heavy  falling  weight, 
and  then  removing  the  shattered  loose  rock  by  raising  it 
in  the  buckets  of  an  ordinary  dredger.  The  rock-break- 
ing rams  are  made  of  iron,  about  42  feet  long  and  9  inches 
square,  with  a  steel-pointed  wedge-shaped  end  or  cutter, 
and  weighing  4  tons.  The  rams  are  raised,  by  hydraulic 
power,  within  a  staging  erected  over  the  bottomless  well  of 
a  bucket  dredger,  and  are  dropped  from  a  height  of  10  to 
20  feet  upon  the  rock.  These  rams,  with  their  wedge- 
shaped  ends,  gradually  shatter  the  rock  after  a  series  of 


1 62  Removal  of  Rock  at  Suez  Canal. 

blows  on  the  same  spot,  and  thus  dispense  with  the  cost 
and  delay  of  boring  and  blasting  rock  under  water.  Ten 
rams  have  been  used  in  one  set,  capable  of  giving  about 
500  blows  in  an  hour.  This  system  has  been  successfully 
applied  to  the  widening  of  the  portion  of  the  Suez  Canal 
which  traverses  rock,  as  much  as  1000  cubic  yards  of 
solid  rock  having  been  raised  in  sixteen  hours  at  Chalouf. 
The  method  appears  primitive,  but  it  has  proved  more 
effectual,  more  rapid,  and  cheaper,  on  the  Suez  Canal 
widening  in  1888,  than  the  ordinary  methods  of  blasting 
rock. 

Blasting  Operations  at  Hell  Gate,  New  York. — The 
channels  of  the  East  River,  leading  from  Long  Island 
Sound  to  New  York  Harbour,  were  obstructed  by  a 
number  of  scattered  reefs,  which  both  imperilled  naviga- 
tion, and  also  rendered  it  difficult  owing  to  the  rapid 
currents  produced  in  the  contracted  channels.  (See  page 
164,  fig.  i.)  Wrecks,  accordingly,  frequently  occurred, 
which  led  to  the  ominous  name  of  Hell  Gate  being 
given  to  the  locality.  The  first  proposals  for  improv- 
ing the  channels,  made  in  1848,  only  contemplated 
the  removal  of  the  highest  pointed  reefs  by  surface 
blasting  (which  was  carried  on  from  1851  to  1853),  owing 
to  the  great  cost  of  extensive  removals  of  submarine 
rocks ;  and  nothing  further  was  done  for  several  years. 
At  last,  in  1868-69,  some  larger  and  wider  detached  rocks 
were  lowered  by  drilling  and  blasting,  the  drilling  being 
effected  from  a  very  strong  barge  at  a  considerable  cost. 
A  more  comprehensive  scheme,  for  the  general  removal 
of  the  rocks  in  the  channels  to  a  depth  of  26  feet  below 
low- water,  was  proposed  in  1869;  and  a  commencement 
was  made  in  the  same  year  at  Hallett's  Point,  from  which 


Undermining  Hallett's  Reef.  165 

a  reef  extended,  connected  with  Long.  Island,  but  jutting 
out  inconveniently  into  the  East  River  at  an  awkward 
bend. 

The  plan  adopted  for  the  removal  of  the  reef  at 
Hallett's  Point,  extending  out  325  feet  from  the  shore, 
and  covering  an  area  of  3  acres  rising  above  the  depth  of 
26  feet  at  low-water,  consisted  in  undermining  the  whole 
of  the  area  with  a  network  of  galleries,  and  then  shattering 
the  roof  and  supports  by  explosives.  (See  page  164,  figs. 
2  and  3.)  A  portion  of  the  reef  above  low-water  was 
enclosed  by  a  watertight  casing,  or  cofferdam,  connected 
with  the  shore  at  both  ends  ;  and  a  shaft  was  sunk  in  this 
enclosure  to  a  depth  of  33  feet  below  low-water.  Large 
galleries  or  headings  were  then  driven  in  radial  lines  by 
boring  and  blasting  from  the  shaft  under  the  reef;  and 
smaller  intermediate  galleries  and  cross  galleries  were 
formed  in  the  rock  under  the  whole  area  of  the  reef  to 
be  removed.  Accordingly,  a  regular  network  of  galleries 
extended  under  the  reef,  having  a  total  length  of  nearly 
a  mile  and  a  half,  resembling  on  a  small  scale  the  catacombs 
of  Rome  and  Paris ;  and  the  roof,  from  6  to  20  feet  thick, 
separating  the  galleries  from  the  river  overhead,  rested 
upon  172  pillars  of  rock,  left  in  piercing  the  galleries,  about 
10  feet  thick  and  from  8  to  22  feet  high.  The  boring  of 
the  holes  in  forming  the  galleries  was  done  at  first  by 
hand,  and  afterwards  by  steam  drills;  but  the  work  pro- 
gressed slowly,  owing  to  the  hardness  of  the  rock,  consisting 
of  hornblende,  gneiss,  and  quartz,  the  shallow  holes  and 
small  charges  necessary  to  avoid  injuring  the  roof,  and 
the  inadequate  sums  yearly  voted  by  Congress  for  the 
work,  so  that  the  galleries  were  not  completed  till  the 
middle  of  1875.  Holes  were  then  drilled  in  the  roof  and 
piers  for  the  cartridges  required  in  the  final  explosion, 


1 66     Exploding  Mines  under  Halleifs  Reef. 

mostly  about  3  inches  in  diameter  and  8f  feet  long. 
Cartridges  filled  with  dynamite,  vulcan  powder,  and  rend- 
rock,  solid  compounds  of  nitro-glycerine,  were  inserted  in 
about  4460  holes,  provided  at  the  end  with  detonating 
charges  of  fulminate  of  mercury.  Altogether  49,900  Ibs. 
of  explosives  were  employed  for  shattering  the  63,100 
cubic  yards  of  rock  in  the  roof  and  piers  of  the  galleries. 
Provision  for  the  simultaneous  firing  of  all  these  mines 
was  made  by  placing  twenty-three  galvanic  batteries  at 
the  spot,  and  connecting  each  of  them  with  a  group  of 
the  mines.  Twenty-three  brass  pins,  each  connected  with 
one  of  the  poles  of  a  battery,  were  suspended  by  a  cord 
over  twenty-three  mercury  clips  in  connection  with  the 
other  poles  of  the  batteries.  When  everything  was 
arranged,  the  galleries  and  shaft  were  flooded  by  the 
admission  of  the  water  from  the  river,  through  a  syphon, 
on  the  23d  of  September  1876,  in  order  to  increase  the 
energy  of  the  explosion  by  somewhat  closing  the  vent  of 
the  holes,  or  tamping  as  it  is  termed,  by  the  pressure  of 
the  water.  The  following  day,  September  24,  1876,  the 
final  explosion  was  effected  by  firing  a  dynamite  cartridge, 
attached  to  the  cord  suspending  the  brass  pins,  by 
electricity  from  the  shore.  The  cord  was  thus  severed  ; 
and  the  brass  pins  dropping  into  the  cups  containing 
mercury,  completed  the  circuit  of  the  batteries,  and  caused 
a  simultaneous  explosion  of  all  the  mines.  Spray  was 
thrown  up  by  the  explosion  to  a  height  of  123  feet ;  but 
no  windows  were  broken  by  the  shock,  and  the  land- 
tremor  produced  was  small.  All  the  shattered  rock 
which  lay  above  the  26  feet  depth  had  to  be  subsequently 
removed  by  grapple  dredgers  ;  and  blocks  which  were  too 
big  to  be  thus  lifted  had  to  be  broken  up  smaller  by 
surface  blasting.  The  removal  of  the  broken  rock  lying 


Driving  Galleries  under  Middle  Reef.        167 

above  the  requisite  level  on  the  reef,  amounting  to  45,300 
cubic  yards,  was  not  completed  till  1882;  so  that  the 
work  occupied  about  twelve  and  a  half  years,  and  it  cost 
£250,420. 

Before  the  final  explosion  at  Hallett's  reef  had  been 
effected,  a  still  greater  undertaking  was  commenced, 
namely,  the  removal,  in  the  same  way,  of  the  Middle 
Reef,  situated  in  mid-channel  between  Astoria  and 
New  York,  and  covering  an  area  of  9  acres  above  the 
depth  of  26  feet  at  low-water  requisite  for  navigation. 
(Seepage  \6^figs.  I,  4,  5,  and  6.)  Two  shafts  were  begun, 
in  1875,  on  a  portion  of  the  rock  above  high-water  level, 
and  were  sunk  to  about  60  feet  below  low-water  level. 
Parallel  galleries  were  driven  from  the  shafts  in  each 
direction,  together  with  galleries  at  right  angles,  extend- 
ing in  a  network,  as  at  Hallett's  reef,  under  the  whole 
area  of  the  reef  to  be  lowered.  The  total  length  of  these 
submarine  galleries  was  a  little  over  4  miles,  about  10 
feet  square  in  section  generally,  but  in  some  places  as  low 
as  4  feet,  and  in  others  33  feet  high.  The  roof,  from  10 
to  20  feet  thick  above  the  galleries,  was  supported  by  467 
pillars  of  rock,  about  15  feet  square,  and  25  feet  apart, 
and  varying  in  height  with  the  height  of  the  galleries. 
Some  fissures  in  the  rock  were  traversed  in  driving  the 
galleries,  which  let  in  a  good  deal  of  water,  but  they  were 
closed  with  cement.  The  great  care  required  in  blasting 
for  forming  the  galleries,  so  as  not  to  injure  the  roof,  and 
the  inadequacy  of  the  yearly  grants,  delayed  the  progress 
of  the  works ;  but  the  drilling  of  the  holes  in  the  roof 
and  pillars  for  the  final  explosion  was  begun  in  1882, 
though  the  galleries  were  not  completed  till  1885. 
There  were  12,560  of  these  holes,  about  3  inches  in 
diameter  and  9  feet  deep,  arranged  from  4  to  5  feet 


1 68        Value  of  Rackarock  as  an  Explosive. 

apart,  and  extending  down  the  pillars  to  33  feet  below 
low-water,  so  that  all  the  rock  might  be  shattered  down 
to  this  depth.  The  charging  of  these  holes  with  explosives 
was  commenced  in  July  1885,  about  two  and  a  half  months 
before  the  final  blast  was  fired. 

The  arrangements  for  this  much  larger  explosion, 
expending  282,730  Ibs.  of  explosives  in  shattering 
270,700  cubic  yards  of  rock,  differed  in  two  important 
particulars  from  the  previous  one  at  Hallett's 
Point ;  for  a  new  explosive  was  used,  and  the  mines 
in  the  roof  and  pillars  were  not  connected  with  the 
batteries.  Rackarock,  which  was  mainly  employed  for 
charging  the  cartridges,  consists  of  a  mixture  of  79  parts 
of  potassium  chlorate,  which  is  a  solid,  with  21  parts  of 
nitro-benzol,  which  is  a  liquid,  and  which  are  therefore 
readily  mixed,  as  the  solid  absorbs  the  liquid.  These  in- 
gredients are  harmless  before  admixture,  and  therefore  can 
be  stored  in  large  quantities  without  danger  of  explosion  ; 
and  the  mixing  is  effected  without  the  great  risk  attending 
the  admixture  of  two  solids  to  form  an  explosive  com- 
pound. Moreover,  rackarock  is  not  so  readily  exploded 
as  dynamite  ;  whilst  its  explosion  under  water  is  more 
effective. 

The  holes  were  filled  with  rackarock  cartridges,  in 
the  top  of  each  of  which  an  exploder  was  inserted, 
consisting  of  a  tube  filled  with  dynamite,  containing 
inside  it  a  small  tube  filled  with  fulminate  of  mercury ; 
arid  at  the  outer  end  of  each  hole  a  dynamite  cartridge, 
15  inches  long,  containing  a  fulminate  exploder,  was 
inserted,  projecting  about  6  inches  out  of  the  hole.  (See 
page  164,  figs.  7  to  n.)  All  these  precautions  were 
necessary  to  insure  the  explosion  of  the  charges  by 
sympathetic  detonation,  resulting  from  the  concussion 


Arrangements  for  Explosion  of  Charges.      169 

produced  by  the  explosion  of  cartridges  placed  in  the 
galleries  and  fired  by  electricity.  These  initial  exploders, 
592  in  number,  were  placed  on  boards  across  the  gal- 
leries, at  intervals  of  25  feet,  and  consisted  of  dynamite 
cartridges  provided  with  fulminate  detonators  connected 
with  the  batteries.  (See  page  164,  fig.  12.)  These  ex- 
ploders were  connected  with  the  twenty-four  batteries  in 
separate  groups,  so  arranged  that  no  two  adjacent  ex- 
ploders should  be  on  the  same  circuit,  in  order  that  if  one 
battery  failed  to  act,  the  exploders  connected  with  it  might 
be  exploded  by  sympathy  by  the  neighbouring  exploders. 
To  secure  the  simultaneous  firing  of  all  the  exploders 
placed  in  the  galleries,  some  mercury,  contained  in  an  iron 
bowl,  was  connected  with  the  negative  poles  of  all  the 
batteries  ;  and  a  thin  glass  tumbler  was  put  in  the  bowl, 
with  some  mercury  in  it  connected  with  all  the  positive 
poles  of  the  batteries,  so  that  the  glass  of  the  tumbler 
alone  prevented  the  closing  of  all  the  circuits.  A  long 
iron  rod,  with  a  pointed  end,  was  placed  in  a  vertical 
position,  with  its  point  resting  on  the  bottom  of  the 
tumbler ;  and  on  the  top  of  the  rod,  a  flat  plate  supported 
a  small  cartridge  which  could  be  fired  by  means  of  wires 
leading  to  a  battery  on  the  shore.  (See page  164,7%;  I3-) 
Water  was  let  into  the  galleries,  by  two  syphons,  on 
the  9th  of  October  1885;  and  when  they  were  filled  with 
water  on  the  following  day,  October  10,  1885,  the  move- 
ment of  a  handle  by  General  Newton's  little  daughter  on 
shore,  at  Astoria,  completed  the  circuit  of  the  shore 
battery,  and  firing  the  small  cartridge  at  the  Middle 
Reef,  drove  down  the  iron  rod,  which,  breaking  the  glass 
tumbler,  completed  the  circuits  of  the  twenty-four  bat- 
teries. The  exploders  along  the  galleries  were  thereby 
fired,  and  by  the  shock  of  their  explosions  fired  the 


170    Transmission  of  Tremor  from  Explosion. 

detonators  in  the  cartridges  projecting  from  the  pillars 
and  roof,  and  produced  a  simultaneous  explosion  of  the 
mines.  A  dull  rumble  was  heard  ;  the  water  rose  in  a 
mass  over  the  site  of  the  reef;  and  spray  shot  up  in  peaks, 
from  100  to  200  feet  high,  as  illustrated  by  the  instan- 
taneous photograph  of  the  explosion,  taken  end  on  from 
Blackwell's  Island.  (See  illustration^)  The  explosion  pro- 
duced no  loud  report  or  great  shock ;  and  little  damage  was 
done,  beyond  the  breakage  of  a  few  panes  of  glass  in  the 
nearest  buildings.  The  earth-wave  produced  by  the  ex- 
plosion was  carefully  recorded  at  various  places  ;  and  the 
rate  of  transmission  of  the  shock  was  found  to  be  more 
rapid  and  more  uniform  when  the  shock  passed  north- 
wards through  rock,  than  when  it  passed  through  drift 
in  an  easterly  direction.  In  travelling  through  drift,  it 
reached  Goat  Island,  a  distance  of  145  miles,  in  59 
seconds,  and  Harvard  College  Observatory,  i82|  miles  off, 
in  3  minutes  40  seconds;  and  in  travelling  through  rock, 
it  reached  West  Point,  42^  miles  distant,  inn  seconds, 
and  Litchfield  Observatory,  174^  miles  away,  in 
45^  seconds. 

Considerable  economy  was  effected  at  Middle  Reef  by 
the  use  of  rackarock,  and  the  explosion  by  sympathy  ;  for 
whereas  the  blast  there  was  six  times  the  blast  at  Hallett's 
Point,  the  expenditure  on  the  final  explosion  was  only 
about  a  third  larger.  The  amount  of  shattered  rock  lying 
above  the  depth  of  26  feet  at  low-water  was  about 
294,000  cubic  yards,  which  has  been  gradually  removed 
by  grapple  dredgers.  The  total  cost  of  the  work  was 
about  £1,070,000,  for  which  expenditure  New  York  has 
got  a  communication  with  the  sea  by  the  East  River  and 
Long  Island  Sound,  with  a  minimum  depth  of  26  feet  at 
low- water,  where  formerly  there  were  numerous  shoals  im- 


Result  of  lowering  Middle  Reef.  1 7 1 

perilling  the  navigation.  Though  headings  for  mines 
have  occasionally  been  carried,  at  a  considerable  depth, 
beyond  the  coast  under  the  sea,  the  system  of  submarine 
mining  had  not  previously  been  adopted  for  lowering 
reefs ;  and  though  costly,  the  removal  of  such  large  reefs 
could  not  have  been  well  accomplished  in  any  other  way. 
The  lowering  of  the  Middle  Reef  was  effected  by  the 
firing  of  the  largest  explosion  ever  attempted,  which 
was  completely  successful,  and  has  provided  the  shipping 
trade  of  New  York  with  an  excellent  direct  channel  to 
the  ocean. 


CHAPTER    IX. 

THE   PORTS   OF   LONDON,   LIVERPOOL,  ANTWERP, 
MARSEILLES,   AND    NEW  YORK. 

THE  foreign  trade  of  a  country  may,  to  a  great  extent, 
be  measured  by  the  size  of  its  ports.  This  is  absolutely 
true  of  Great  Britain,  Australia,  New  Zealand,  India, 
and  other  countries  separated  from  foreign  lands  by 
the  sea  or  mountain  barriers.  It  is  true,  also,  though 
to  a  somewhat  less  extent,  of  continental  nations  pos- 
sessing a  convenient  seaboard  ;  for  trading  nations  do 
not  confine  their  trade  within  the  narrow  limits  of 
adjacent  countries,  if  they  can  obtain  a  sea-going  trade 
with  the  various  countries  of  the  world.  Seaports,  ac- 
cordingly, form  an  important  element  in  the  commercial 
prosperity  of  nations ;  and  their  development  is  essential 
to  the  increase  of  trade.  Many  ports  are  of  ancient 
origin,  but  their  development  is  in  all  cases  of  recent 
date  ;  and  several  ports  have  only  come  into  existence 
within  the  present  century.  For  instance,  the  large 
ports  of  Hull,  the  Tyne,  Glasgow,  and  Havre,  possessed 
very  little  accommodation  for  shipping  previous  to  the 
present  century ;  whilst  Cardiff,  Barrow,  and  Middles- 
borough  have  sprang  into  existence  as  ports  in  the  last 
fifty  years. 


Growth  of  the  Port  of  London.  173 

Port  of  London. — At  the  beginning  of  the  present 
century  London  possessed  only  one  dock,  namely,  the 
Greenland  Dock,  constructed  in  1660,  forming  part 
now  of  the  Surrey  Commercial  Docks,  with  an  area  of 
1 2  acres,  and  quays  along  the  river  having  a  total  length 
of  rather  under  a  mile.  Considerable  additions  to  the 
dock  accommodation  along  the  Thames  were  made 
early  in  the  century,  by  the  construction  of  the  East  and 
West  India  Docks,  the  London  Docks,  the  Surrey  and 
Commercial  Docks,  and  lastly,  in  1828,  the  St  Katherine 
Docks,  close  to  London'  Bridge.  All  the  important  sub- 
sequent dock  extensions  have  been  made  during  the  last 
thirty-five  years. 

A  tendency  has  been  manifested,  in  most  of  the  more 
recent  large  dock  extensions  of  recent  times  in  the  Port 
of  London,  to  place  the  docks  lower  down  the  river, 
where  more  open  space  is  available,  land  is  cheaper,  and 
the  river  is  both  broader  and  less  crowded  with  shipping. 
The  first  large  addition  to  the  dock  accommodation  of 
London  since  1828  was  the  opening  of  the  Victoria  Dock 
and  Basin  in  1855,  adding  90  acres  of  water  to  the  dock 
area  of  the  port.  This  dock,  like  most  of  the  earlier 
docks,  is  situated  in  a  low-lying  tract  of  land  between  two 
bends  of  the  river,  where  the  excavations  from  the  docks 
could  be  utilised  for  raising  the  adjacent  land  to  form 
quays,  and  where  an  entrance  lock  could  be  easily  made 
to  open  on  the  river  from  the  extremity  of  the  docks. 
The  Victoria  Dock,  nearly  opposite  Woolwich,  is  lower 
down  the  river  than  any  of  the  earlier  docks  ;  it  is  3000  feet 
long,  and  1050  feet  wide,  and  is  provided  with  several 
jetties  on  the  north  side,  to  increase  the  quay  accommoda- 
tion for  vessels  ;  and,  like  most  of  the  other  London  docks, 
it  has  a  basin  between  the  main  dock  and  the  entrance 


1 74  Victoria,  and  Millwall  Docks. 

lock,  which  joins  the  river  a  little  beyond  Bow  Creek  below 
Blackwall.  The  lock  was  given  a  width  of  80  feet,  20  feet 
wider  than  any  previous  lock  on  the  Thames  ;  and  its 
length  of  350  feet  was  greater  than  the  length  of  the 
earlier  locks.  An  interesting  feature  of  this  dock  is  the 
arrangement  of  the  repairing,  or  graving  docks  in  connec- 
tion with  it.  Usually  these  graving  docks  are  made  suffi- 
ciently deep  for  a  vessel  of  the  largest  size  to  be  floated  in ; 
the  gates  at  the  entrance  are  then  closed,  the  water  is 
pumped  out,  the  vessel  is  propped  up,  and  the  repairs 
are  executed.  The  Victoria  graving  docks,  however,  are 
made  shallow ;  and  the  vessel,  on  entering  the  channel 
leading  to  the  graving  docks  from  the  main  dock,  passes 
over  a  pontoon  sunk  at  the  bottom  of  the  channel,  which 
is  then  lifted  out  of  water,  by  hydraulic  rams  underneath, 
raising  the  vessel  suitably  supported  on  it.  The  water 
flows  out  of  the  open  valves  of  the  pontoon,  which  are 
then  closed  ;  and  the  rams,  descending  again,  leave  the 
vessel  resting  on  the  floating  pontoon,  which  is  hauled 
into  one  of  the  shallow  docks  for  repairs. 

The  Millwall  Docks,  in  the  Isle  of  Dogs,  were  next 
opened  in  1868,  having  a  water  area  of  35  acres,  and  an 
entrance  lock  of  the  same  width  and  depth  as  the  Victoria 
Dock  lock,  but  450  feet  long,  being  an  increase  of  100  feet. 
In  1870,  the  opening  of  the  South  West  India  Dock  added 
32  more  acres  to  the  water  area  of  the  docks  of  London. 
This  dock,  which  stretches  across  the  Isle  of  Dogs,  has 
a  lock  at  each  end  like  the  other  West  India  docks,  the 
lower  and  larger  lock  serving  for  the  entrance  of  large 
vessels,  and  the  upper  lock  being  used  by  the  river  barges, 
which  convey  goods  from  the  vessels  up  to  wharves  along- 
side the  river.  This  dock  is  also  provided  with  a  basin 
between  the  main  entrance  lock  and  the  dock,  which  facili- 


Description  of  Albert  Dock,  London.        175 

tates  the  entrance  and  exit  of  a  number  of  vessels  by  being 
made  level  with  the  river  outside  near  high-water,  so  that 
vessels  pass  in  or  out  without  the  delay  of  locking;  whilst 
the  level  of  water  in  the  dock  is  not  altered.  The  chief 
novel  feature  in  the  Millwall,  and  South  West  India  docks 
was  the  employment  of  a  large  proportion  of  concrete  at 
the  back  of  the  face  of  brickwork  in  the  quay  walls  sur- 
rounding them,  which,  owing  to  the  abundance  of  good 
river  gravel  found  in  the  excavations,  reduced  consider- 
ably the  cost  of  the  walls. 

The  Albert  Dock,  forming  an  extension  of  the  Victoria 
Dock,  and,  though  a  distinct  dock,  connected  with  it  by  a 
channel,  was  opened  in  1880.  This  dock,  6500  feet  long 
and  490  feet  wide,  is  narrower  than  the  Victoria  Dock,  and 
has  no  jetties.  Including  a  basin,  it  has  an  area  of  84  acres, 
and  with  its  basin  and  entrance  lock,  extends  to  the  further 
side  of  the  bend  of  the  river  which  passes  by  Woolwich;  so 
that  the  two  docks  stretch  right  across  this  very  wide  bend, 
with  entrances  into  the  Thames  at  each  end  about  3  miles 
apart.  The  Albert  Dock  lock,  though  given  the  same 
width  of  80  feet  as  the  Victoria  Dock  lock,  was  made 
550  feet  long  instead  of  350  feet,  and  was  given  a  depth  of 
30  feet  at  high-water  spring  tides  instead  of  28  feet,  indi- 
cating the  advance  considered  expedient  in  the  lapse  of 
twenty-five  years.  When,  however,  the  Tilbury  Docks 
were  in  progress,  holding  out  a  prospect  for  shipping  to 
enter  the  docks  at  any  state  of  the  tide,  the  Victoria  and 
Albert  Dock  Company  deemed  it  advisable  to  increase 
their  accommodation  by  a  deeper  lock,  which  was  accord- 
ingly constructed,  near  the  first  Albert  Dock  lock,  with  a 
depth  of  36  feet  at  high-water  spring  tides,  but  with  a 
length  and  width  similar  to  the  first  lock.  The  quay  walls 
round  the  Albert  Dock  were  built  entirely  of  concrete, 


1 76  Blasting  Wall  at  Approach  to  New  Lock. 

made  with  the  gravel  from  the  excavations,  mixed  with  an 
eighth  part  of  Portland  cement.  Concrete  under  such  con- 
ditions is  very  economical ;  it  also  requires  little  plant  or 
skilled  labour,  and  can  be  rapidly  built  up.  In  order  to 
connect  the  new  lock  and  a  small  extension  with  the  basin, 
520  feet  in  length  of  the  basin  wall  had  to  be  removed, 
which,  after  it  had  been  reduced  at  the  back  by  blasting  to 
a  uniform  thickness  of  about  6  feet,  was  effected  by  drilling 
a  number  of  holes  at  the  back  in  the  remaining  front 
portion  of  the  wall,  filling  them  with  gelatine  dynamite, 
and  firing  all  the  charges  simultaneously  by  electricity. 
There  were  1450  holes,  placed  4  feet  apart,  filled  with 
2900  Ibs.  of  explosive;  and  the  charges  were  fired  on  Good 
Friday  morning  1886,  which  was  chosen  on  account  of 
the  absence  of  men  from  work,  giving  greater  security 
against  injury,  and  to  avoid  interfering  with  the  dock 
traffic.  The  explosion  produced  a  loud  report,  but  did 
not  cause  any  damage  to  adjacent  property ;  and  the  wall 
fell,  broken  to  pieces,  in  a  heap  in  the  water.  The  Victoria 
and  Albert  docks  form  part  of  the  dock  property  of  the 
London  and  St  Katherine  Dock  Company. 

The  Tilbury  Docks  were  commenced  in  1882  by  the 
East  and  West  India  Dock  Company,  with  the  object  of 
offering  more  ample  accommodation  lower  down  the 
Thames  than  the  other  dock  companies.  They  are  situ- 
ated on  low-lying  land  at  Tilbury,  opposite  Gravesend  ; 
and  they  consist  of  an  outer  tidal  basin  of  19^  acres, 
communicating  directly  with  the  river ;  a  lock,  700  feet 
long  and  80  feet  wide,  leading  from  the  basin  to  the 
docks  ;  and  a  main  dock  leading  to  three  parallel  branch 
docks,  each  1 500  feet  long,  with  sheds  and  sidings  along 
each  side,  having  a  total  area  of  57  J  acres.  The  basin 
has  been  excavated  to  a  depth  of  26  feet  at  low-water 


Description  of  the  Tilbury  Docks.  177 

spring  tides,  so  that  vessels  can  always  remain  afloat  in 
it ;  and  as  the  outer  sill  of  the  lock  is  only  I  foot  higher, 
or  45  feet  below  high-water  spring  tides,  vessels  can  enter 
or  leave  the  docks  at  any  state  of  the  tide.  Two  channels, 
parallel  to  the  lock,  each  contain  a  pair  of  graving  docks  ; 
and  the  largest  and  deepest  channel  could  be  used  as  a 
lock  in  case  of  necessity.  Owing  to  the  silty,  alluvial 
nature  of  the  soil,  the  foundations  for  the  walls  had  to 
be  carried  to  a  considerable  depth,  and  in  some  cases 
were  founded  upon  piles;  and  as  the  bottom  of  the  dock 
is  38  feet  below  high-water  spring  tides,  the  walls,  made  of 
concrete  with  brick  facing,  had  to  be  raised  about  44  feet 
above  the  dock  bottom,  higher  than  any  previous  dock  walls 
on  the  Thames.  These  docks  were  opened  in  April  1886. 

Hydraulic  machinery  for  opening  and  closing  the  dock 
gates,  the  sluice  gates,  and  the  swing  bridges,  for  moving 
the  cranes  and  lifts,  and  for  turning  the  capstans,  was  pro- 
vided at  the  South  West  India  Dock  on  its  opening  in 
1870 ;  it  has  been  extended  also  to  the  older  docks,  and 
has  always  been  supplied  to  the  more  recent  docks  in  the 
Port  of  London.  Hydraulic  power  is  specially  adapted 
for  the  intermittent  work  of  docks  ;  for  the  power  can  be 
gradually  stored  up  by  means  of  accumulators,  to  be  em- 
ployed more  rapidly  than  it  could  be  generated  at  periods 
of  a  press  of  work,  such  as  at  high-water. 

The  construction  of  docks,  like  that  of  the  foundations 
of  bridges,  involves  a  great  amount  of  difficult  work  ;  and 
the  quays,  sheds,  sidings,  swing  bridges,  and  tops  of  the 
gates,  which  are  alone  visible  when  the  docks  are  filled 
with  water,  furnish  a  very  inadequate  impression  of  the 
hazardous  and  intricate  works  required  in  making  a  dock. 
Temporary  cofferdams  have  to  be  made  for  keeping  out 
the  water;  large  pumping  machinery  has  to  be  constantly 

M 


178    Difficulties  attending  Dock  Construction. 

working  to  keep  the  foundations  dry ;  deep  foundations 
have  to  be  excavated  to  reach  a  reliable  stratum  ;  great 
care  has  to  be  taken  to  prevent  the  sliding  forward  of  the 
wall  in  filling  up  at  the  back  of  high  dock  walls  before  the 
water  is  let  into  the  dock  ;  the  masonry  in  the  locks  has 
to  be  very  accurately  dressed  to  receive  the  gates  ;  the 
gates  have  to  be  very  carefully  fitted,  secured,  and  made 
watertight ;  sluiceways  have  to  be  formed  through  the 
walls  of  the  lock,  built  so  as  to  resist  the  pressure  and  rush 
of  water  through  them ;  and  the  foundations  of  the  floor  of 
the  lock  have  to  be  made  secure  against  pressure  and 
percolation  under  a  head  of  water.  The  superstructure 
and  piers  of  bridges  and  viaducts  are  always  in  evidence 
to  attest  the  skill  of  their  designers ;  whereas  docks,  and  to 
a  great  extent  waterworks,  can  be  only  justly  appreciated 
during  construction,  the  works  being  in  great  measure 
hidden  from  view  after  their  completion ;  whilst  break- 
waters, being  built  mostly  under  water,  can  be  only 
judged  of  by  their  effects. 

The  water  area  of  the  docks  of  London  has  been 
nearly  doubled  since  1855,  and  at  present  amounts  to  558 
acres,  exclusive  of  shallow  timber  ponds  ;  whilst  the  facili- 
ties for  the  admission  of  vessels  of  large  draught,  and  for 
loading  and  unloading,  have  been  immensely  increased 
during  the  same  period.  Moreover,  whereas  the  Port  of 
London,  fifty  years  ago,  only  reached  as  far  as  Blackwall, 
6f  miles  from  London  Bridge,  it  now  extends  to  Graves- 
end,  26  miles  below  London  Bridge. 

Port  of  Liverpool. — Though  the  first  dock  was  com- 
menced at  Liverpool  in  1709,  the  port  progressed  very 
slowly  up  to  the  beginning  of  the  present  century,  as  it 
only  possessed  34  acres  of  water  area  in  1816.  Whilst 


Extension  of  the  Port  of  Liverpool.          179 

increasing  more  rapidly  after  this  period,  so  that  its  dock 
area  reached  1 08  acres  in  1846,  its  chief  advance  has 
occurred  within  the  last  fifty  years ;  for  the  Port  of  Liver- 
pool now  possesses  docks  with  a  total  water  area  (includ- 
ing Birkenhead,  which  was  incorporated  with  it  in  1855) 
of  521  acres.  Thus,  the  dock  accommodation  of  the 
port  is  nearly  fivefold  what  it  was  fifty  years  ago.  Docks 
have  been  gradually  extended  north  and  south  of  the 
older  docks,  on  the  Liverpool  side ;  whilst  docks  have  been 
constructed  at  Birkenhead,  on  the  opposite  side  of  the 
Mersey,  on  the  site  of  Wallasey  Pool.  The  docks  extend 
at  Liverpool,  along  the  Mersey,  in  a  continuous  line  of 
nearly  6  miles,  only  broken  near  the  centre  by  the  ap- 
proach road  to  the  great  landing-stage.  The  most 
recent  dock  extensions  on  the  north  side,  nearest  the  sea, 
where  the  largest  docks  are  situated,  have  been  made  on 
land  reclaimed  from  the  river  foreshore,  and  surrounded 
with  concrete  quay  walls.  The  southern  extensions,  on 
the  contrary,  encroach  upon  rising  ground,  so  that  excava- 
tions have  been  needed  in  forming  portions  of  the  quays  ; 
whilst  the  docks  have  been  excavated  out  of  the  solid 
sandstone  rock,  so  that  in  some  places  it  was  only 
necessary  to  face  the  rock  with  ashlar  masonry,  instead  of 
building  a  dock  wall.  The  earlier  Liverpool  docks  were 
of  small  area,  rarely  exceeding  10  acres  ;  but  the  more 
recent  docks  are  larger,  of  which  the  biggest  are  the 
Canada,  Langton,  and  Hornby  Docks,  of  about  18  acres 
each ;  the  Huskisson  Dock,  of  30  acres  ;  and  the  Alexandra 
Dock,  of  44  acres,  opened  in  1880.  The  East  and  West 
Docks  at  Birkenhead  are  larger,  however,  than  any  of  the 
Liverpool  docks,  having  areas  of  59f,  and  52  acres  re- 
spectively ;  but  they  are  not  so  large  as  either  the  Albert 
or  Victoria  docks  on  the  Thames,  of  71,  and  74  acres  ; 


.  1 80     Entrances  at  Liverpool  and  Birkenhead. 

whilst  the  Cavendish  Dock  at  Barrow  exceeds  them  all, 
with  an  area  of  102  acres. 

The  docks  at  Liverpool  are  all  connected  together  by 
passages  or  entrances  to  the  north  and  south  of  the  land- 
ing-stage approach,  which  divides  them  into  two  distinct 
groups  ;  and,  instead  of  being  approached  by  locks,  as  on 
the  Thames,  access  is  provided  generally  along  the  Mersey, 
at  a  few  places,  through  entrances  with  a  single  pair  of 
gates,  which  are  opened  a  short  time  before  high-water, 
and  closed  on  the  turn  of  the  tide.  These  entrances  are 
in  some  cases  approached  through  a  tidal  basin,  which 
shelters  the  vessels,  and  facilitates  their  entry  or  exit. 
There  are  entrances  and  locks  at  Liverpool  and  Birken- 
head 100  feet  in  width,  provided  originally  for  paddle- 
wheel  steamers  which  have  been  superseded  by  screw- 
steamers  ;  and  the  largest  new  entrances  are  65  feet  wide. 
The  largest  lock  at  Liverpool  is  498  feet  long,  leading 
to  the  Canada  Dock  ;  and  the  deepest  entrances  at  Liver- 
pool and  Birkenhead  are  2  feet  below  the  lowest  low-tide, 
affording  a  depth  of  23^  feet  at  high-water  neap  tides, 
and  31  feet  at  spring  tides  ;  but  the  construction  of  deeper 
entrances  is  in  contemplation,  to  allow  of  a  longer  period 
for  the  entrance  or  exit  of  vessels. 

The  large  quantity  of  sand  and  silt  carried  in  suspen- 
sion by  the  Mersey  readily  deposits  in  the  sheltered  tidal 
basins  leading  to  the  docks,  and  would  soon  impede  the 
access  if  not  cleared  away  ;  and  a  bank  of  sand,  known  as 
the  Pluckington  Bank,  stretches  across  the  entrances  of 
the  older  docks,  on  the  southern  side,  rising  above  low- 
water  level.  In  constructing  the  deep  Langton  Dock 
entrances,  opening  into  the  Canada  Tidal  Basin,  four  iron 
pipes,  8  feet  in  diameter,  encased  in  concrete,  were  carried 
under  the  concrete  floor  of  the  basin  in  front  of  the  en- 


Sluices  for  removing  Sand  and  Silt.         1 8 1 

trances,  having  several  vertical  outlets,  3  feet  in  diameter, 
on  a  level  with  the  floor,  spread  over  this  area.  By  open- 
ing sluice  gates  at  low-water  spring  tides,  the  water 
from  the  docks  is  admitted  into  one  or  more  of  these 
pipes,  and  issuing  with  great  force  from  the  outlets  on  the 
floor,  sweeps  away  the  accumulation  of  silt,  and  keeps 
the  passage  clear.  Another  set  of  sluices,  with  numerous 
horizontal  outlets  at  a  low  level,  are  placed  along  the 
jetties  on  each  side  of  the  entrance  to  the  tidal  basin  ;  and 
the  current  of  water  from  the  docks,  let  out  at  low-tide 
from  these  sluices,  maintains  the  passage  between  the 
basin  and  the  river.  Another  series  of  sluices  higher  up 
the  river,  fed  with  water  from  the  southern  docks  at  low 
tide,  keep  the  northern  end  of  Pluckington  Bank  from 
extending  under  the  floating  landing-stage.  As  many  as 
twenty-three  of  the  largest  steamships,  of  an  aggregate 
burden  of  34,200  tons,  and  thirty-five  smaller  vessels,  have 
been  let  in  or  out  of  the  docks,  through  the  Canada  Basin, 
in  a  single  tide  during  2\  hours  before  high-water. 

The  huge  floating  landing-stage  forms  a  prominent 
feature  in  front  of  the  Liverpool  Docks.  Rising  and  fall- 
ing with  the  tide,  it  is  connected  with  the  land  by  seven 
hinged  girder  bridges,  which  vary  in  inclination  with  the 
height  of  the  stage,  and  by  a  floating  bridge,  550  feet  long 
and  35  feet  broad,  which  provides  an  inclined  roadway 
suitable  for  carriage  traffic  at  any  state  of  the  tide.  This 
stage,  2063  feet  long  and  80  feet  wide,  supported  on 
138  iron  pontoons,  affords  a  platform  4  acres  in  extent, 
and  is  used  by  about  two  million  persons  in  a  year,  for 
steamers  and  ferryboats  come  alongside  it.  There  are  two 
similar, but  smaller,  floating  stages  on  the  Birkenhead  shore. 

The  ports  of  London  and  Liverpool  stand  unrivalled 
amongst  the  ports  of  the  world,  both  in  dock  accommoda- 


.182  London  and  Liverpool  compared. 

tion  and  trade.  They  are  very  considerably  ahead  of  the 
other  ports  of  Great  Britain  in  the  tonnage  of  vessels 
trading  with  them,  the  Tyne  ports  coming  third  ;  whilst 
they  are  much  more  in  advance  in  respect  of  the  values 
of  their  merchandise,  for  Hull  stands  third,  with  a  fifth 
of  the  value  of  the  Liverpool  trade.  London  is  first  as 
regards  imports,  and  Liverpool  as  regards  exports ;  but, 
on  the  whole,  London  is  the  first  port  of  the  world,  both 
in  the  tonnage  of  its  vessels  and  in  the  value  of  its 
trade,  as  well  as  in  its  dock  accommodation  and  facility 
of  access. 

Port  of  Antwerp. — The  good  depth  of  the  Scheldt  and 
Flemish  enterprise  made  Antwerp  one  of  the  principal 
ports  of  Europe  from  the  I3th,  to  the  middle  of  the  i;th 
century,  when  it  was  closed  to  vessels,  by  treaty,  till  the 
end  of  the  last  century.  It  was  provided  with  two  docks 
and  some  river  quays  early  in  the  present  century  ;  but, 
like  London  and  Liverpool,  its  main  development  as 
a  port  has  been  accomplished  within  the  last  fifty  years. 
Indeed,  there  are  few  ports  which  show  as  remarkable 
a  progress  in  recent  years  as  Antwerp.  Up  to  1860,  it 
only  possessed  two  docks,  having  an  area  of  about 
21  acres,  and  some  quays  along  the  river;  it  now  has 
1 20  acres  of  docks;  and  its  river  quays,  entirely  remodelled, 
reconstructed,  and  extended,  have  a  total  length  of  2  miles 
\\  furlongs.  The  Kattendyk  Dock  was  opened  in  1860  ; 
and  shortly  afterwards  the  removal  of  the  lines  of  fortifi- 
cation to  a  greater  distance  from  the  town  enabled  the 
space  of  the  old  demolished  fortifications  to  be  utilised  in 
extending  the  city  and  port.  The  docks  were  accord- 
ingly extended,  and  the  Kattendyk  Dock  was  prolonged, 
making  its  area  32  acres;  and  in  1880  the  dock  area  had 


River  Quays  at  Antwerp.  183 

reached  120  acres.     Two  new  docks  were  begun  in  1883, 
on  the  site  of  the  old  North  Citadel,  namely,  the  Africa 
Dock,  for  large  transatlantic  steamers,  and  the  America 
Dock,  for  the  petroleum  trade,  having  together  an  area  of 
50  acres,  with  a  depth  of  30  feet  at  high-water.     These 
docks  will  raise  the  dock  area  of  the  Port  of  Antwerp  to 
170  acres.     Meantime  the   river  quay   walls  were  built 
along  a  rectified  line  of  the  river,  which  necessitated  the 
building  of  a  great  portion  of  the  wall  in  the  alluvial 
bed  of -the  river,  at  some  distance  from  the  bank  in  the 
upper  part.     The  foundations  of  this  portion  of  the  quay 
wall  were  excavated  down  to  a  solid  bottom,  and  brought 
up  to  low-water  by  aid  of  caissons,  furnished  with  a  work- 
ing chamber  supplied  with  compressed  air.    These  caissons 
were  82  feet  long  and  29^  feet  wide,  with  a  bottomless 
chamber,  6J  feet  high,  at  the  bottom,  and  plate-iron  sides 
enclosing  the  area  above  the  roof;  and  they  were  floated 
into  position  between  two  long  barges,  having  a  stage 
erected  over  them,  from  which  the  caisson  was  suspended  by 
chains.    The  upper  part  of  the  caisson  was  then  filled  with 
concrete,  and  the  wall  built  upon  it,  under  the  protection  of 
the  plate-iron  sides  ;  and  the  caisson  gradually  sank  under 
the  increasing  weight  till  it  touched  the  bed  of  the  river, 
when  its  position  was  carefully  adjusted,  and  the  building 
of  the  wall  continued   above,  till   sufficient  weight   was 
attained  to  prevent  the  compressed  air  raising  the  caisson. 
The  working  chamber  was  then  filled  with  compressed 
air,  access  for  the  men  and  materials  to  this  chamber  being 
provided  by  seven  shafts  furnished  with  air-locks  at  the 
top ;  and  the  men  entering  the  working  chamber,  lit  with 
electric    light,    proceeded  with   the   excavations   till   the 
caisson  reached  a  firm  bottom,  from  34  to  52  feet  below 
low-water.     The  wall  having,  in  the  meantime,  been  built 


184         Eq^lipment  and  Trade  of  Antwerp. 

up,  the  working  chamber  and  shafts  were  filled  with  con- 
crete ;  and  the  plates  surrounding  the  wall  above  the  roof 
of  the  chamber,  and  the  barges  and  staging,  were  removed 
to  serve  for  another  length  of  wall.  The  portion  of  the 
river  bed  between  the  wall  and  the  old  river  bank  was 
filled  in,  and  formed  a  quay.  The  quays  along  the  river 
have  been  very  well  equipped  with  sidings,  sheds,  and 
hydraulic  travelling  cranes. 

The  trade  of  Antwerp  has  responded  to  the  improved 
accommodation  afforded,  for  it  has  augmented  rapidly 
since  1881 ;  and  the  tonnage  of  vessels  trading  with  the 
port  about  equals  that  of  the  Tyne  ports,  which  stand 
third  in  this  respect  amongst  the  ports  of  the  United 
Kingdom,  and  exceeds  the  tonnage  of  vessels  entering 
any  of  the  French  ports. 

Port  of  Marseilles. — The  foremost  port  of  France  is 
Marseilles,  which,  as  regards  the  tonnage  of  its  vessels,  is 
only  exceeded  by  four  English  ports,  namely,  London 
Liverpool,  the  Tyne  ports  and  Cardiff.  Like  the 
ports  already  described,  Marseilles,  though  an  ancient 
port,  has  been  only  really  developed  within  the  last 
fifty  years  ;  for  up  to  1852  its  accommodation  consisted 
merely  of  the  natural  shelter  provided  by  the  Old  Har- 
bour, an  inlet  from  the  coast  of  67  acres,  to  the  south- 
east of  the  present  port,  which  had  been  surrounded 
by  quays,  as  well  as  a  small  canal  and  basin  opening  out 
of  it,  which  raised  the  total  water  area  of  the  port  to 
72  acres. 

The  Port  of  Marseilles,  unlike  the  river  ports  of 
London,  Liverpool,  and  Antwerp,  just  described,  is 
situated  upon  the  shore  of  a  tideless  sea.  Shelter  inside 
rivers  is  denied  to  the  ports  of  countries  bordering  tideless 


Peculiarities  of  Marseilles  Basins.  185 

seas,  owing  to  the  deltas  formed  by  the  rivers  flowing  into 
them,  which  obstruct  their  outlets.  Accordingly,  ports 
on  the  Mediterranean  Sea  have  to  be  situated  on  the  sea- 
coast  ;  and  artificial  shelter  has  to  be  provided  where,  as 
in  most  cases,  natural  shelter  is  deficient.  This  shelter 
on  the  sea-coast  has  to  be  furnished  by  breakwaters, 
which  protect  an  area  between  them  and  the  shore  in 
which  vessels  can  lie  in  safety,  and  discharge  and  take 
in  cargoes.  At  Marseilles  a  detached  breakwater  has 
been  constructed  parallel  to  the  coast,  commenced  near 
the  Old  Harbour,  and  extended  towards  the  north-west, 
which  both  serves  in  places  as  a  quay  on  its  sheltered 
side,  and  also  protects  a  considerable  water  area  between 
it  and  the  coast,  which  is  divided  into  a  series  of  basins 
by  jetties  projecting  from  the  shore.  These  basins  are 
surrounded  by  quays,  constructed  upon  the  breakwater,  the 
wide  jetties,  and  quay  walls  along  the  shore,  and  serve  like 
docks  for  the  purposes  of  trade.  They  differ,  however, 
from  the  ordinary  form  of  docks  adjoining  tidal  rivers  in 
not  requiring  gates  to  keep  the  water  at  a  uniform  level, 
owing  to  the  absence  of  appreciable  tidal  oscillation. 
They  differ,  also,  in  the  method  of  construction  of  the  quay 
walls  ;  for  the  breakwater  and  jetties,  having  to  be  built 
in  the  sea,  consist  of  a  mound  of  stones  deposited  in  the 
water,  surmounted  by  a  quay  bordered  by  concrete  walls, 
faced  with  stone  above  the  water  line.  On  the  sea  side  of 
the  breakwater,  a  high  parapet  wall  takes  the  place  of 
a  quay  wall ;  and  large  concrete  blocks  protect  the  sea 
slope.  The  first  addition  to  the  port  was  the  Joliette  Basin, 
commenced  in  1844,  and  opened  in  1852,  having  an  area  of 
54  acres,  and  entered  by  a  canal  from  the  Old  Harbour, 
and  direct  from  the  sea,  through  a  partially  sheltered  outer 
harbour  of  56  acres.  The  adjoining  Lazaret  and  Arenc 


1 86  Progress  of  Port  of  Marseilles. 

basins,  51  acres  in  area,  and  the  Railway  Basin,  of  41  acres, 
were  opened  in  1863;  and  the  National  Basin,  with  an 
area  of  105  acres,  was  completed  in  1881,  raising  the 
total  sheltered  area  of  the  port  to  325  acres.  The  exten- 
sion, moreover,  of  the  breakwater,  nearly  half-a-mile 
beyond  the  National  Basin,  forms  a  partially  sheltered 
outer  harbour  of  44  acres  at  this  end,  facilitating  and 
protecting  the  entrance  to  the  National  Basin.  Wide 
passages  between  the  breakwater  and  the  ends  of  the 
jetties  furnish  communication  between  the  basins ;  whilst 
two  swing  bridges  across  the  passage  between  the  Joliette 
and  Lazaret  basins,  and  a  railway  swing  bridge  across  the 
passage  between  the  Arenc  and  National  basins,  connect 
the  quay  along  the  breakwater  with  the  land.  The  break- 
water has  a  length  of  about  2 \  miles.  Six  graving  docks 
have  been  constructed,  opening  out  of  an  inner  basin  ;  and 
the  quays  are  well  equipped  with  warehouses,  sheds, 
sidings,  and  hydraulic  machinery. 

The  works  commenced  in  1844  have  quite  transformed 
the  Port  of  Marseilles,  for  they  have  not  only  more  than 
quadrupled  the  sheltered  area  of  the  port,  but  they  have 
also  added  very  extensive  and  thoroughly  equipped  quays, 
compared  with  which  the  Old  Harbour  provides  very 
imperfect  accommodation.  The  prosperity  of  the  port 
has  been  established  during  this  period ;  and  the  growth 
of  its  trade  has  followed  so  closely  upon  the  enlargements 
of  the  port,  that  fresh  extensions  are  under  consideration. 

Port  of  New  York. — The  City  of  New  York  is  most 
favourably  situated  for  a  maritime  trade,  on  account  of  its 
insular  position,  with  deep  water  on  each  side  along  the 
Hudson  and  East  rivers,  and  also  because  its  water  front- 
age is  well  sheltered  from  storms,  whilst  close  to  the  ocean. 


Wharves  of  Port  of  New  York.  187 

The  docks  of  New  York,  as  they  are  termed,  are  really 
merely  quay  walls,  or  bulkheads,  extending  continuously 
along  the  river  fronts  of  the  southern  part  of  New  York, 
with  projecting  timber  jetties.  No  artificial  shelter  is 
required,  as  protection  is  afforded  by  Long  Island  to  the 
east,  and  by  the  mainland  to  the  west ;  and  as  the  mean 
tidal  rise  is  only  4f  feet,  floating  docks  shut  off  from  the 
sea  by  gates  are  quite  unnecessary.  Wharves  have  been 
gradually  extended  with  the  growth  of  the  city ;  but, 
owing  to  the  varied  ownership  of  the  river  frontages,  the 
walls  and  jetties  were  constructed  at  first  according  to  the 
ideas  of  each  individual  owner,  without  any  systematic 
arrangement  or  control.  Though  some  supervision  was 
introduced  early  in  the  present  century,  in  the  interests  of 
the  public,  it  was  only  in  1870  that  a  special  department 
was  constituted  for  reconstructing  the  wharves  according 
to  a  comprehensive,  definite  plan.  The  city  is  gradually 
acquiring  the  river  frontages ;  and  the  line  of  quay  wall  is 
being  carried  out  far  enough  into  the  water  to  form  a 
street  alongside  the  river  to  accommodate  the  trade. 
Timber  jetties  are  being  erected  at  right  angles  to  the 
quay  wall,  with  intervals  between  them  of  1 50  to  200  feet ; 
and  they  extend  from  400  to  500  feet  into  the  river  on 
the  west  side  of  the  island,  with  a  width  of  60  to  80  feet ; 
but  on  the  east  side  they  are  rather  smaller.  Owing  to 
the  soft  alluvial  nature  of  the  beds  of  the  East  and  Hudson 
rivers,  light  quay  walls  of  concrete  and  masonry  have 
been  built  on  piles,  surrounded  by  a  mound  of  rubble 
stone  to  keep  the  piles  in  place.  On  the  East  River,  and 
on  part  of  the  Hudson  River,  the  piles  reach  a  solid  stratum, 
and  afford  a  firm  foundation  for  the  wall  ;  but  in  parts  of 
the  Hudson  River  the  silt  was  proved  to  exceed  200  feet 
in  thickness,  so  that  at  these  places  the  piles  have  to  bear 


1 88       Extension  of  Wharves  at  New  York. 

the  weight  of  the  wall  by  the  adherence  simply  of  the 
enveloping  silt,  which  prevents  any  movement  of  the  pile 
after  being  left  undisturbed  for  some  hours.  By  the  new 
system,  the  length  of  wharfmg  is  being  increased  from 
28  miles,  which  was  its  length  in  1870,  to  37  miles;  and 
the  area  afforded  by  the  piers  is  being  trebled,  in  addition 
to  the  gain  of  a  street  alongside  the  quay. 

More  than  half  the  foreign  trade  of  the  United  States 
passes  through  the  Port  of  New  York ;  and  New  York  is 
only  excelled  in  the  value  of  its  exports  and  imports  by 
London  and  Liverpool. 


CHAPTER    X. 

THE  BREAKWATERS  OF  TABLE  BAY,  ALEXANDRIA, 
BOULOGNE,  COLOMBO,  DOVER,  AND  NEWHAVEN 
HARBOURS. 

THOUGH  some  small  artificial  harbours  were  formed 
in  ancient  times,  and  the  breakwater  protecting  the 
large  harbour  of  Cherbourg  was  commenced  towards 
the  close  of  the  last  century,  the  development  of 
breakwater  construction  has  taken  place  in  the 
present  century ;  and  most  of  the  prominent  ex- 
amples of  breakwaters  have  been  constructed  within 
the  last  fifty  years.  The  harbour  works  of  Plymouth, 
Kingstown,  and  Howth,  and  the  extensions  at  Algiers 
Harbour,  were,  indeed,  carried  out  in  the  early  part  of 
this  century ;  but  these  breakwaters  are  of  the  simplest 
type,  such  as  was  adopted  in  earlier  times,  namely,  a 
mound  of  rubble  stone,  protected  by  masonry  pitch- 
ing on  the  exposed  face,  or,  in  the  case  of  Algiers, 
with  large  concrete  blocks.  A  great  impulse  was 
given  to  the  construction  of  harbours  of  refuge  on 
the  coasts  of  Great  Britain  by  a  letter  from  the  Duke 
of  Wellington,  in  1842,  on  the  unprotected  and  de- 
fenceless state  of  the  shores  of  the  country,  which 
resulted  in  the  commencement,  about  1847,  of  the 


190  Principles  of  forming  Harbours. 

harbours  of  Dover,  Portland,  Holyhead,  Alderney,  and 
St  Catherine's,  Jersey,  by  the  Government.  Numerous 
harbours,  also,  have  been  more  recently  formed  in 
various  parts  to  provide  shelter  for  accommodating 
and  developing  trade,  as  for  instance  Madras,  Colombo, 
Newhaven,  Boulogne,  Brest,  Genoa,  Odessa,  Alexandria, 
Table  Bay,  Charleston,  Galveston,  and  the  lake  harbours 
of  Chicago,  Oswego  and  Buffalo. 

The  size  and  form  of  a  harbour  depend  upon  the 
natural  conditions  of  the  site,  and  the  capital  that  is 
available,  or  can  profitably  be  expended  upon  its  con- 
struction. Sometimes  a  bay  is  sufficiently  sheltered  by 
the  land  to  need  only  a  detached  breakwater  across  its 
wide  outlet,  in  order  to  convert  it  into  a  harbour,  with 
entrances  between  the  ends  of  the  breakwater  and  the 
shore,  of  which  Plymouth,  Cherbourg,  and  Delaware 
harbours  are  examples.  Occasionally  a  single  break- 
water, carried  out  from  a  projecting  point  of  a  bay, 
affords  adequate  shelter  to  the  water  area  partly  en- 
closed between  it  and  the  shore  of  the  bay,  a  method 
adopted  at  Holyhead,  Alderney,  Colombo,  Alexandria, 
and  Table  Bay.  The  absence  of  any  suitable  sheltered 
bay  in  the  neighbourhood  of  the  place  for  which 
a  harbour  is  required,  sometimes  necessitates  the 
formation  of  a  purely  artificial  harbour  on  a  straight 
line  of  coast,  entirely  sheltered  by  two  or  more  break- 
waters, as  exemplified  by  Kingstown  and  Madras  har- 
bours, and  the  complete  design  of  Boulogne  Harbour, 
as  yet  only  partially  carried  out.  The  arrangements, 
accordingly,  of  breakwaters  for  forming  a  harbour 
are  mainly  dependent  upon  local  circumstances,  and  are 
not  capable  of  much  modification.  The  chief  progress 
has  therefore  been  effected  in  the  form  and  materials  of 


SECTIONS,    OF    BREAKWATERS. 


TABUE         BAV 


ALEXANDRIA. 


H  w  6.  s  .~r 


OOV  ER. 


OOl_OM  BO. 


Types  of  Breakwater  Constriction.          193 

breakwaters,  and  in  the  methods  adopted  for  their  con- 
struction. 

There  are  three  types  of  breakwaters,  namely,  the 
rubble  stone  or  concrete  block  mound,  where  a  heap 
of  hard  material  is  deposited  in  the  ocean  along  the 
line  chosen  for  the  breakwater ;  a  mound  of  rubble 
stone  to  form  the  base,  surmounted  by  a  thick  upright 
wall ;  and,  lastly,  a  solid  wall  carried  up  from  the 
bottom.  Table  Bay  and  Alexandria  breakwaters  illus- 
trate the  first  type;  Boulogne  and  Colombo  break- 
waters show  two  different  forms  of  the  second  type ; 
whilst  the  most  notable  instance  of  the  third  type  is 
the  Admiralty  Pier  at  Dover.  (See  page  192.)  The 
first  type  follows  the  old  method  of  construction,  and 
may  be  adopted  where  materials  are  abundant,  where 
the  width  occupied  by  the  breakwater  is  immaterial, 
and  where  no  quay  is  required.  The  second  type  re- 
quires less  material  than  the  first ;  but  its  superstructure 
has  to  be  solidly  constructed  to  resist  the  waves  break- 
ing against  it.  The  third  type  requires  least  material ; 
but  it  involves  still  more  careful  construction,  and  diving 
work.  It  is  chiefly  adapted  for  a  hard  bottom,  in  no 
great  depth  of  water ;  and,  like  the  second  type,  it 
provides  a  quay  accessible  in  fine  weather. 

Table  Bay  Harbour. — This  harbour  has  been  formed 
by  a  breakwater  carried  out,  in  a  north-easterly  direction, 
from  a  projecting  point  in  Table  Bay  to  the  north  of  Cape 
Town,  so  as  to  afford  some  shelter  from  the  north-west, 
in  which  direction  the  bay  is  open  to  the  Atlantic  Ocean. 
The  breakwater  runs  out  in  a  straight  line  due  north-west 
for  about  2400  feet,  and  then  bends  a  little  towards  the 
east,  to  protect  the  water  area  bordering  the  adjacent  coast 

N 


1 94     Construction  of  Table  Bay  Breakwater. 

more  effectually  from  the  north.  The  breakwater  consists 
of  a  mound  of  rubble  stone  (see  section,  page  192),  de- 
posited from  staging,  which  the  sea  has  levelled  on  the 
exposed  side  to  a  slope  of  about  I  in  9  for  some  dis- 
tance below  low-water.  The  stone  has  been  excavated 
from  a  neighbouring  site,  part  of  which  has  already 
been  utilised  for  an  inner  basin.  The  work  was  begun 
in  1860,  and  reached  1900  feet  from  the  shore  in 
1868,  in  a  depth  of  30  feet;  and  an  extension  was 
commenced  in  1881,  which  will  give  the  breakwater 
a  total  length  of  3700  feet,  and  carry  it  into  a  depth 
of  about  50  feet  of  water.  This  breakwater  furnishes 
a  recent  example  of  the  simplest  form  of  breakwater, 
constructed  in  the  simplest  possible  manner,  but  with 
a  large  expenditure  of  material,  which,  however,  is  close 
at  hand. 

Alexandria  Harbour. — A  new  harbour  was  commenced, 
in  1870,  by  sheltering  an  extensive  bay  to  the  south- 
west of  Alexandria,  by  means  of  a  breakwater,  which 
starts  near  Eunostos  Point,  at  the  south-western  extremity 
of  Pharos.  After  running  parallel  with  the  shore  for 
about  3500  feet,  the  breakwater  bends  towards  the 
shore  in  a  nearly  southerly  direction,  reaching  a  total 
length  of  9675  feet,  and  leaving  an  entrance  between 
its  extremity  and  the  shore,  3340  feet  in  width,  with 
a  maximum  depth  of  60  feet.  A  sheltered  area  has 
thereby  been  obtained  of  1400  acres,  possessing  a  mini- 
mum depth  of  30  feet. 

The  breakwater  is  composed  of  a  mound  of  large 
concrete  blocks,  20  tons  in  weight,  on  the  sea  side,  with 
rubble  stone  on  the  harbour  side.  (See  section,  page  192.) 
The  concrete  blocks  were  deposited  first  on  the  outside  of 


System  of  forming  Alexandria  Breakwater.    195 

the  mound  ;  and  the  rubble  stone  was  placed  at  the  back, 
under  their  shelter.  The  blocks  forming  the  lower 
part  of  the  mound  were  let  down  into  the  water  along 
an  inclined  plane  on  the  deck  of  a  barge;  but  the 
blocks  near,  and  above  the  water  level  were  deposited 
by  a  floating  steam  derrick  or  crane.  The  block  was 
lifted  by  the  derrick  from  an  attendant  barge,  by 
means  of  slings,  which  clasped  the  block  at  its  four 
side  edges,  and  which  readily  released  the  block,  when 
brought  into  its  proper  position,  by  a  slight  pull  of  a 
rope  which  unloosed  the  clutches.  The  concrete  blocks, 
made  of  broken  stone,  sand,  and  Portland  cement,  re- 
duced the  amount  of  material  required  for  the  mound, 
and  increased  its  power  of  resisting  the  sea,  owing  to 
the  size  of  the  blocks.  The  rubble  stone  was  deposited 
from  barges,  through  trap-doors  in  the  bottom  and  sides. 
The  breakwater  was  completed  in  1872,  about  two 
years  only  from  its  commencement,  or  nearly  at  the 
rate  of  a  mile  in  a  year,  a  very  remarkable  rate  of 
progress  when  compared  with  the  many  years  occupied 
in  the  construction  of  Cherbourg  and  Plymouth  break- 
waters, and  even  with  the  progress  of  breakwaters  of 
more  recent  date. 

Boulogne  Harbour. — The  condition  of  the  harbours  of 
Boulogne  and  Calais  are  always  of  interest  to  England, 
as  they  are  the  nearest  ports  to  the  English  coast ; 
and  any  improvements  in  their  depth  or  accessibility 
facilitates  communication  with  the  Continent.  The 
access  to  the  Port  of  Calais  has  been  improved  by  a 
rectification  of  its  entrance  channel,  which  is  guided 
by  parallel  jetties  on  each  side ;  by  a  large  sluicing 
basin  of  220  acres,  formed  on  the  strand,  from  which 


196       Large  Harbour  Works  at  Boulogne. 

a  powerful  scouring  current  is  discharged  at  low  tide 
into  the  entrance  channel  to  maintain  its  depth ;  and 
lastly,  by  the  deepening  of  the  approach  channel,  through 
the  sandbanks  outside,  by  dredging  with  sand-pumps, 
whereby  a  depth  is  now  maintained  of  13  feet  below 
low- water  of  the  lowest  spring  tides,  where,  up  to  1875, 
the  depth  did  not  exceed  2\  feet  below  the  same  level. 
Accordingly,  Calais  Harbour  can  be  entered  by  the 
mail  steamers  from  England  at  any  state  of  the  tide ; 
whereas  formerly  steamers,  drawing  only  7-^  feet  of  water, 
could  not  enter  the  port  near  low-water  of  spring  tides. 

At  Boulogne,  works  on  a  much  larger  scale  than  at 
Calais  have  been  partially  constructed,  with  the  object 
of  transforming  Boulogne  Harbour  from  a  small  jetty 
harbour,  like  Calais,  inaccessible  near  low-water,  into 
a  spacious  harbour,  sheltered  by  breakwaters,  affording 
ample  depth  for  vessels  of  the  largest  draught  at  any 
state  of  the  tide.  This  harbour  was  commenced  in 
1879;  and  a  breakwater  has  been  constructed,  starting 
from  the  shore  about  \\  miles  to  the  south-west  of  the 
old  jetty  harbour,  and,  after  being  carried  out  about 
4500  feet  from  the  shore,  curving  round  and  going  to- 
wards the  Old  Harbour,  nearly  parallel  to  the  coast. 
Some  quays  have  also  been  formed  under  the  shelter  of 
the  breakwater,  extending  a  short  distance  out  from  the 
land.  The  breakwater  already  built  is  only  the  south- 
western portion  of  the  design ;  and  it  is  proposed  to 
carry  out  another  breakwater  from  the  shore,  in  the  line 
of  the  north-eastern  jetty  of  the  Old  Harbour,  a  little 
more  than  ij-  miles  from  the  land,  and  then  to  close 
the  wide  gap  between  the  outer  extremity  of  this  break- 
water and  the  end  of  the  return  arm  of  the  south-western 
breakwater  by  a  detached  breakwater,  leaving  entrances 


Mixed  Type  of  Boulogne  Breakwater.       197 

between  each  end  of  it  and  the  extremities  of  the  two 
other  breakwaters,  facing  north  and  west  respectively, 
820  and  490  feet  in  width. 

The  breakwater  is  composed  of  a  mound  formed 
with  small  stones  in  the  interior,  surrounded  with 
larger  stone,  and  concrete  blocks  of  24  tons  on 
the  sea  slope,  surmounted  by  a  solid  masonry  super- 
structure founded  about  10  feet  above  low-water  of 
spring  tides.  (See  section,  page  192.)  The  section  of 
this  breakwater  exhibits  a  marked  economy  in  material 
in  proportion  to  the  depth  of  water,  when  compared 
with  the  section  of  Table  Bay  breakwater,  and  even  with 
the  Alexandria  Breakwater  section.  The  material  forming 
the  mound  was  at  first  tipped  from  waggons  run  out 
from  the  shore ;  but  afterwards  barges  were  employed 
for  depositing  it  to  increase  the  rate  of  progress. 
The  mixed  type  of  mound  and  upright  wall,  to  which 
this  breakwater  belongs,  has  been  adopted  for  a  large 
number  of  breakwaters  ;  but  generally  the  wall,  or  super- 
structure, is  commenced  at,  or  below  the  level  of  low- 
water,  which  reduces  still  further  the  amount  of  material 
required. 

The  cost  of  this  harbour  has  been  estimated  at 
;£  1, 280,000  ;  but  when  it  is  completed,  it  will  be  second 
only  to  Cherbourg  amongst  the  French  ports  on  the 
Channel.  The  south-west  breakwater  affords  some  pro- 
tection, and  shelters  the  entrance  to  the  Old  Harbour 
from  south-west  gales. 

Colombo  Harbour. — Colombo  is  the  port  for  the  large 
and  increasing  trade  of  Ceylon ;  but,  till  the  breakwater 
works  were  commenced  in  1874,  the  bay  in  which  the 
harbour  is  situated  was  exposed  to  the  monsoons,  greatly 


198      Site  and  Shelter  of  Colombo  Harbour. 

impeding  the  unloading  and  lading  of  vessels  by  the 
swell  which  they  cause.  The  south-west  monsoon,  which 
prevails  from  May  till  November,  is  the  worst  wind ; 
and,  accordingly,  a  western  breakwater  has  been  carried 
out  from  a  projecting  point  at  the  western  extremity 
of  the  bay,  running  nearly  parallel  with  the  shore  on  the 
other  side  of  the  bay,  for  a  distance  of  4212  feet,  in  a 
straight  line,  except  towards  the  end  which  is  slightly 
curved  inwards  to  increase  the  shelter  afforded.  The 
water  area,  at  low-water,  sheltered  by  the  breakwater 
is  502  acres,  of  which  242  acres  have  a  minimum  depth 
of  26  feet,  part  of  which  has  been  obtained  by 
dredging  some  shallow  portions  to  that  depth.  Some 
wharves  and  jetties  have  been  constructed  under  the 
shelter  of  the  breakwater,  along  the  southern  shore  of 
the  bay. 

The  breakwater  consists  of  a  rubble  mound,  deposited 
from  a  barge,  with  a  concrete  block  wall  built  upon  it, 
34  feet  wide,  and  founded  from  16  to  20  feet  below  low- 
water  of  spring  tides,  the  rise  of  tide  at  Colombo  being 
only  2  feet.  (See  section,  page  192.)  The  mound  was 
carried  out  700  feet,  on  the  average,  in  advance  of  the 
wall,  so  as  to  allow  it  at  least  a  year  to  consolidate 
under  the  action  of  the  sea  before  erecting  the  super- 
structure upon  it,  to  guard  against  the  settlement  of  the 
wall.  The  depth  at  which  the  wall  was  founded  secured 
it  against  being  undermined  by  the  waves ;  and  the 
mound,  moreover,  was  raised  on  each  side  of  the  wall, 
above  the  foundations,  by  tipping  stone  over  the  sides 
of  the  wall,  and  was  further  protected  on  the  sea 
slope  by  concrete  bags  laid  close  alongside  the  sea 
face  of  the  wall.  The  concrete  block  wall,  or  super- 
structure, was  built  by  depositing  the  blocks  in  a 


Construction  arid  Cost  of  Colombo  Breakwater.    1 99 

series  of  sloping  rows,  with  the  bottom  of  each  row  in 
advance  of  the  top,  so  that  each  section  of  the  breakwater, 
having  the  thickness  of  one  block,  leaned  to  some  extent 
on  the  adjacent  inner  section,  but  was  free  to  slide  if  un- 
equal settlement  of  the  mound  occurred.  Each  block  was 
laid  in  an  inclined  position  from  the  overhanging  arm 
of  a  counterbalanced  crane,  which  travelled  along  the 
completed  breakwater  as  the  work  progressed.  This 
system  of  construction,  which  dispenses  with  staging 
liable  to  be  injured  by  storms,  and  provides  against 
cracks  from  unequal  settlement,  was  inaugurated  at 
the  Kurrachee  Harbour  works  in  1870,  and  was  sub- 
sequently adopted  at  Madras  Harbour  in  1876;  and  it 
has  also  been  employed  for  breakwaters  at  Reunion 
Island,  and  at  Mormugao  on  the  west  coast  of  India. 
The  concrete  blocks  in  each  section  at  Colombo  are 
from  16^  to  31  tons  in  weight;  they  are  laid  at  an 
inclination  of  I  in  3,  and  have  a  thickness  of  5^  feet. 
Each  section  contains  three  or  four  tiers  of  blocks ;  and 
the  sections,  or  rows,  were  eventually  connected  together, 
after  settlement  had  ceased,  by  filling  grooves  left  in  the 
face  of  each  row  with  concrete  in  bags,  and  by  a  concrete- 
in-mass  capping  along  the  top  of  the  breakwater. 

The  work  was  completed  in  1885,  having  cost 
£705,200;  and  the  revenues  of  the  harbour  in  1883  and 
1884  averaged  about  £34,000  a  year.  The  harbour,  being 
open  to  the  north,  is  still  exposed  to  the  north-east  mon- 
soon ;  and  a  detached  northern  breakwater  has  been  pro- 
posed for  sheltering  it  from  this  quarter,  leaving  an 
entrance  of  800  feet  between  the  two  breakwaters  for 
the  passage  of  vessels. 

Dover    Harbour.— -The    position    of    Dover,   at     the 


2OO  Refuge  Harbour  at  Dover. 

narrowest  part  of  the  English  Channel,  and  the  nearest 
point  of  the  English  coast  to  France,  has  been  always 
regarded  of  great  strategical  importance.  When,  therefore, 
in  1845,  measures  were  being  taken  by  the  Government 
to  establish  harbours  at  important  places  on  the  coast, 
both  for  refuge  and  defence,  Dover  was  naturally  one 
of  the  sites  selected  for  a  harbour ;  and  the  form,  extent, 
and  shelter  of  the  proposed  harbour,  were  the  subject  of 
the  most  careful  investigations.  Dover  is  situated  in  a 
slight  indentation  of  the  coast,  protected  somewhat  from 
the  south-west  by  the  projecting  part  of  the  coast  from 
which  the  Admiralty  Pier  starts,  and  under  the  shelter 
of  which  the  old  port  was  formed.  The  approved  scheme, 
commenced  in  1847,  consisted  of  an  oblong  harbour 
of  about  600  acres,  enclosed  by  breakwaters  extending 
as  far  to  the  east  of  the  Castle  as  the  Admiralty  Pier  is 
to  the  west,  having  a  maximum  length  parallel  to  the 
coast  of  about  7300  feet,  and  a  maximum  width  out  from 
the  coast  of  about  4200  feet.  The  present  breakwater  or 
pier  represents  the  short,  western,  most  exposed  side  of 
this  grand  scheme  ;  and  of  the  five  harbours  commenced 
in  1847,  Dover,  the  most  important,  remains  also  the 
most  incomplete.  This  breakwater,  however,  has  been  of 
great  service  for  the  continental  traffic,  and  shelters  vessels 
on  its  inner  side  during  southerly  or  westerly  gales,  and 
on  its  outer,  or  south-western  side  during  easterly  gales. 
It  is  also  of  great  interest  as  having  been  the  first  large 
breakwater  built,  in  an  exposed  situation,  on  the  upright 
wall  system  from  the  bottom,  without  any  mound.  (See 
section,  page  192.) 

The  breakwater  has  been  built  of  a  series  of  courses 
of  concrete  blocks  up  to  high-water  level,  and  con- 
crete-in-mass  hearting  above;  both  sides  of  the  wall 


Upright  Wall  Breakwater  at  Dover.       201 

being  faced  with  granite  throughout  for  the  greater 
part  of  the  wall,  but  only  above  low-water  level  at 
the  outer  part,  to  reduce  the  cost.  The  foundation 
courses  were  laid  upon  the  solid  chalk  bottom,  very 
carefully  levelled  by  divers  in  a  diving-bell,  entailing 
a  considerable  expense  and  a  large  amount  of  time. 
The  wall  has  been  given  a  slight  inclination,  or  batter, 
on  each  face,  and  is  surmounted  by  a  parapet  wall, 
which,  during  westerly  gales,  protects  the  paved  quay 
on  to  which  the  trains  run  alongside  the  mail  steamers. 
The  breakwater  was  terminated,  at  its  present  length 
of  2100  feet,  in  1871,  extending  into  a  depth  of  about 
45  feet  at  low- water.  The  total  amount  paid  to  the 
contractors  for  the  construction  of  the  breakwater  was 
about  £679,300. 

The  Dover  Breakwater  is  larger  in  section,  and  ex- 
tends into  deeper  water  than  any  breakwater  hitherto 
constructed  as  a  simple,  solid,  upright  wall  resting  directly 
on  the  sea  bottom.  The  advantages  of  the  system  are, 
that  the  smallest  possible  amount  of  material  is  required 
for  its  construction  ;  that,  when  resting  on  a  firm  bottom, 
it  is  not  liable  to  settlement  like  a  superstructure  built 
upon  a  mound  of  rubble  stone ;  and  that  it  is  not  nearly 
so  subject  to  injury  from  waves  as  a  loose  rubble  mound. 
The  disadvantages  of  slow  progress  and  large  cost, 
experienced  at  Dover,  are  not  necessarily  inherent  in 
the  system  ;  and  there  is  no  doubt  that,  with  the  pro- 
gress in  the  methods  of  breakwater  construction  achieved 
in  recent  years,  any  extension  of  the  Dover  Breakwater 
could  be  effected  at  a  much  cheaper  and  more  rapid 
rate. 

New  haven  Harbour. — The    Port   of    Newhaven.    the 


2O2          Description  of  Newhaven  Harbour. 

nearest  port  on  the  English  Channel  to  London,  has 
established  a  considerable  trade  with  Dieppe,  the  nearest 
port  to  Paris.  It  has  been  formed  at  the  mouth  of  the 
river  Ouse,  in  Seaford  Bay,  a  part  of  the  coast  which  has 
at  various  times  been  suggested  as  a  suitable  site  for  a 
harbour  of  refuge.  Though  the  depth  at  the  mouth  of 
the  river  was  improved  at  various  times  by  the  erection 
and  extension  of  jetties,  which  directed  and  concentrated 
the  outflow  across  the  beach,  aided  by  the  straightening 
of  the  river  in  1863-64,  the  bar  of  shingle  was  only 
forced  a  little  further  out ;  so  that  only  a  tidal  service 
could  be  obtained.  In  1878,  however,  authority  was 
obtained  for  constructing  a  breakwater  a  little  to  the 
west  of  the  mouth  of  the  river,  under  the  shelter 
of  which  a  channel,  12  feet  deep  at  low-water  spring 
tides,  could  be  dredged  across  the  bar,  and  the  port, 
with  its  quays  alongside  the  river,  could  be  made 
accessible  for  vessels  of  moderate  draught  at  all  states 
of  the  tide. 

The  breakwater  proceeds  out  straight  from  the  shore, 
in  a  southerly  direction,  for  1000  feet,  and  then  curves 
gradually  towards  the  east,  so  as  to  protect  the  entrance 
to  the  river  from  west  round  nearly  to  south.  The 
breakwater  was  designed  to  have  a  length  of  2800  feet, 
of  which  1482  feet  have  been  carried  out  at  a  cost  of 
£89,000.  The  bottom  is  chalk,  as  at  Dover ;  but  instead 
of  spending  time  and  money  in  dressing  the  chalk  under 
water  to  a  level  bed  for  the  concrete  blocks,  the  concrete- 
in-mass,  of  which  the  breakwater  is  built,  has  been  fitted 
to  the  irregular  bottom.  The  portion  of  the  breakwater 
up  to  low-water  was  built  of  concrete  in  bags,  deposited  by 
opening  flap  doors  at  the  bottom  of  the  well  of  a  barge  ; 
and  each  bag,  filled  with  100  tons  of  concrete,  extends  right 


Concrete  used  for  Newhaven  Breakwater.    203 

across  the  whole  width  of  the  break  water.  The  special 
steam  hopper-barge,  for  depositing  the  bags,  having  been 
brought  alongside  the  quay  in  the  river,  its  well  was  loosely 
lined  with  jute  canvas ;  and  after  the  concrete  had  been 
rapidly  placed  in  the  well,  the  sacking  was  sewn  together 
over  the  concrete,  whilst  the  barge  steamed  to  the  place  of 
deposit  for  forming  the  breakwater.  As  soon  as  the  flap 
doors  closing  the  bottom  of  the  well  of  the  barge  were 
released,  the  concrete  bag  fell  through  the  water  into 
position,  being  protected  from  the  wash  of  the  water  by 
the  canvas  lining ;  whilst  the  loose  bag,  before  the  con- 
crete had  set,  adjusted  itself  to  any  irregularities  of  the 
bottom,  or  of  the  previously  deposited  bags.  As  soon  as 
a  sufficient  length  of  breakwater  had  been  thus  raised 
about  2  feet  above  low-water,  the  upper  portion  of  the 
breakwater  was  formed  by  depositing  concrete-in-mass 
inside  timber  framing  enclosing  the  space  above  the  bag 
foundations.  The  breakwater,  accordingly,  forms  a  solid 
upright  wall,  with  a  slight  inclination  on  each  face,  com- 
posed of  a  series  of  heavy  bag  blocks  below,  laid  right 
across  the  breakwater,  and  a  monolithic  mass  of  concrete 
above  low-water.  This  system,  which  was  introduced  for 
the  foundations  of  the  Aberdeen  Harbour  breakwaters, 
on  a  rocky  bottom,  in  1871,  is  economical  for  long  break- 
waters, is  rapid  in  execution,  and  forms  a  compact  break- 
water. The  inevitable  absence  of  a  perfect  connection 
between  the  bags  below  low-water  is  rendered  immaterial 
by  their  large  size  ;  and,  moreover,  the  weight  of  the  con- 
tinuous mass  of  concrete,  forming  the  portion  of  the  break- 
water above  low-water,  effectually  consolidates  the  lower 
portion. 

The  construction  of  breakwaters  capable  of  success- 
fully withstanding  the  continuous  shocks  of  waves  hurled 


204  Improvements  in  Breakwater  Construction. 

against  them  with  apparently  irresistible  force  during 
storms,  requires  the  utmost  skill  and  experience  of  the 
engineer.  The  sea,  like  the  most  insidious  of  foes, 
infallibly  discovers  any  weak  point  in  a  breakwater,  and 
rapidly  extends  any  damage  it  may  have  produced. 
The  force  of  the  sea  cannot  be  measured  with  precision 
like  the  strains  on  a  bridge ;  but  its  power  has  been 
demonstrated  by  the  injuries  structures  in  the  sea  have 
experienced  during  storms,  and  by  the  way  in  which 
huge  masses  of  masonry  have  been  dislodged  by  waves. 
The  size  of  the  waves,  however,  in  any  particular  locality, 
and  therefore  the  force  to  be  controlled,  depends  upon  the 
depth  of  water  in  front,  the  direction  of  the  strongest  and 
most  prevalent  wind,  and  the  distance  this  wind  may 
have  travelled  over  a  continuous  stretch  of  sea. 

The  three  types  of  breakwaters,  namely,  the  old  rubble 
mound  system,  the  mound  with  superstructure,  and  the 
modern  upright  wall  system,  are  all  employed  at  the 
present  day.  The  rubble  mound,  however,  has  been 
strengthened  by  the  use  of  large  blocks  of  stone  or  con- 
crete on  its  exposed  upper  sea  slope  ;  and  its  construction 
has  been  greatly  expedited  by  suitable  appliances.  The 
mixed  type  of  breakwater,  which  is  available  for  con- 
siderable depths  of  water,  has  been  freed  from  the  dis- 
location, and  the  consequent  injury  in  storms,  due  to 
unequal  settlement  of  the  superstructure  upon  a  yielding 
mound,  by  the  adoption  of  the  sloping-block  system  ;  and 
the  use  of  an  overhanging  crane  for  depositing  the  blocks 
has  enabled  staging  in  the  sea  to  be  dispensed  with,  and  has 
very  materially  increased  the  rate  of  progress  attainable. 
The  upright  wall  system,  so  costly  in  its  first  employment 
at  Dover,  has  been  greatly  facilitated  and  cheapened  by 
the  use  of  concrete  in  large  bags  under  water  for  large 


Concrete  employed  for  Fishery  Piers.        205 

works,  and  concrete-in-mass  deposited  within  frames 
under  water  for  small  piers,  where  the  cost  of  the  special 
plant  required  for  the  bags  would  be  prohibitive. 

Breakwater  construction  has,  accordingly,  made  rapid 
strides  in  recent  years  ;  and  the  employment  of  Portland 
cement  concrete  has  enabled  numerous  fishery  piers  to  be 
constructed,  with  great  benefit  to  the  fishery  trade  and 
the  seafaring  population,  which  could  not  have  been 
contemplated  in  former  times. 


CHAPTER   XI. 

IMPROVEMENT   WORKS   ON   THE  TYNE,   THE  SEINE, 
THE  MAAS,  THE  DANUBE,  AND  THE  MISSISSIPPI. 

RIVERS  afford  access  to  sheltered  ports,  and  also  to  the 
interior  of  a  country ;  and  the  class  of  trade  they  can 
accommodate  depends  on  the  navigable  depth  of  their 
channels.  A  broad  distinction  has  to  be  drawn  between 
rivers  flowing  into  tidal  seas,  like  the  rivers  of  Great 
Britain  and  of  the  north  and  west  coasts  of  France, 
and  rivers  discharging  into  seas  like  the  Black  Sea,  the 
Mediterranean,  and  the  Gulf  of  Mexico,  in  which  the  rise 
of  the  tide  is  barely  perceptible.  The  volume  of  water 
flowing  through  the  outlet  of  a  tidal  river  is  very  greatly 
increased  by  the  tidal  water  from  the  sea,  so  that  the 
estuary  and  outlet  channels  of  a  tidal  river  are  much 
larger  than  the  freshwater  discharge  alone  of  the  river 
could  maintain.  Thus  the  Thames,  the  Severn,  the 
Mersey,  and  the  Seine  have  estuaries  quite  out  of  pro- 
portion to  the  flow  from  the  basins  which  they  drain. 
The  outlets,  however,  of  rivers  discharging  into  tideless 
seas  can  only  be  maintained  by  the  volume  of  fresh- 
water coming  down  these  rivers,  which  is  proportionate 
to  the  amount  of  the  rainfall  which  reaches  the  water- 
courses, and  the  area  of  their  basins.  Tidal  and  tide- 
less  rivers  also  differ  essentially  in  the  nature  of  the 


RIVER  IMPROVEMENTS. 


Contrast  between  Tidal  and  Tide  less  Rivers.   209 

shoals,  or  bar,  found  at  their  mouths.  The  sea  constantly 
tends  to  form  a  continuous  beach  along  the  coast,  com- 
posed of  the  detritus  of  the  adjacent  shores,  which  is  only 
partially  prevented  by  the  ebb  and  flow  of  the  tide  at  the 
mouths  of  tidal  estuaries,  aided  by  the  freshwater  dis- 
charge of  the  river  ;  so  that,  except  under  specially  favour- 
able conditions  of  the  form  of  the  estuary,  the  outlet  is 
frequently  obstructed  by  a  shoal.  In  the  case  of  tidal 
risers,  the  material  brought  down  by  a  river,  in  its  course 
from  the  uplands,  is  prevented  from  depositing  in  any 
particular  p  ace  by  being  kept  in  constant  motion  by  the 
ebb  and  flow  of  the  tide,  so  that  it  is  dispersed  in  the 
large  estuary  into  which  many  tidal  rivers  open  near 
their  outlet,  or  is  gradually  carried  out  to  sea.  All  the 
detritus,  however,  brought  down  by  a  river  flowing  into  a 
tideless  sea  is  gradually  deposited  beyond  the  mouth  of 
the  river,  owing  to  the  checking  of  the  river  current 
when  entering  the  open  sea.  The  material  thus  deposited 
forms  a  fan-shaped  shoal,  protruding  into  the  sea  in 
advance  of  the  coast  line,  constantly  progressing  sea- 
wards by  the  accession  of  fresh  sediment  ;  and  through 
it  the  enfeebled  river  current  finds  an  outlet, 
through  shallow,  diverging  channels  to  the  sea,  to  which 
the  term  delta  has  been  applied,  on  account  of  the 
shape  assumed  by  the  channels  and  shoal.  Well-known 
instances  of  such  outlets  are  furnished  by  the  deltas  of  the 
Nile,  the  Rhone,  the  Danube,  and  the  Mississippi.  (See 
page  208.)  Shoals,  moreover,  are  found  in  various  parts 
of  rivers,  where  ridges  of  hard  material  or  rock  across  the 
channel  prevent  the  natural  deepening  by  scour,  and 
cause  rapids,  or  where  a  great  expansion  in  width  leads 
to  a  corresponding  reduction  in  depth.  The  object  of  all 
river  improvement  works  is  to  form  a  tolerably  uniform 


2 1  o          Early  Tyne  Improvement  Works. 

channel,  with  a  minimum  depth  adequate  for  the  require- 
ments of  navigation ;  and  the  most  important  part  of  a 
river,  and  the  portion  in  which  the  chief  difficulties  are 
generally  experienced,  is  at  the  outlet,  and  for  some  dis- 
tance above,  where  a  deep  channel  is  requisite  to  provide 
access  for  sea-going  vessels. 

River  Tyne. — The  first  works  undertaken  on  the  river 
Tyne  for  obtaining  an  improved  channel  between  New- 
castle and  the  sea,  a  distance  of  loj  miles,  were  com- 
menced in  1843.  At  that  time  there  was  a  depth  of  only 
2  feet,  at  one  place,  in  the  deepest  channel  at  low-water 
spring  tides,  and  14  J  feet  at  high-water  ;  and  at  some  parts 
the  shoals  rose  above  low-water  level  in  the  centre  of  the 
river.  Between.  1843  and  1858  the  river  was  regulated 
by  carrying  out  projecting  jetties  or  groins  from  the 
banks,  joined  eventually  at  their  ends  by  longitudinal 
mounds  of  rubble  stone,  called  training  walls,  with  the 
object  of  improving  the  depth  by  the  increase  in  scour 
thereby  produced.  A  small  amount  of  dredging  was  also 
carried  out  every  year,  at  first  by  one  dredger,  and  even- 
tually by  three  dredgers,  up  to  1860.  A  moderate  amount 
of  improvement  had  been  thereby  effected ;  but  even  in 
1860  there  was  a  depth  of  only  6  feet  over  the  bar  at 
the  mouth  at  low-water  of  spring  tides ;  and  no  vessels 
of  over  20  feet  draught  could  enter  or  leave  the  Tyne, 
even  at  high-water  spring  tides.  A  series  of  shoals, 
moreover,  existed  between  Shields  and  Newcastle,  so  that 
vessels  of  15  feet  draught  could  only  get  up  to  New- 
castle, even  at  high-water  spring  tides,  by  following  a 
winding  channel  between  the  shoals. 

Piers,  or  breakwaters,  were  commenced  at  the  mouth 
of  the  river  in  1856,  for  protecting  vessels  in  easterly 


Piers  and  Dredging  for  Improving  Tyne.    2  1 1 

gales  ;  and  these  piers,  by  the  shelter  afforded,  have 
facilitated  the  removal  of  the  bar  at  the  mouth.  These 
piers  are  now  approaching  completion,  having  been  carried 
out  gradually,  in  proportion  as  the  Tyne  Improvement 
Commissioners  could  periodically  allot  funds  for  the  pur- 
pose. They  consist  of  a  superstructure,  built  of  concrete, 
and  faced  with  masonry,  founded  upon  a  low  rubble  stone 
mound,  deposited  from  barges,  and  protected  on  the  top  of 
the  sea  slope  by  concrete  blocks.  (See  page  208.)  The 
superstructures  were  at  first  constructed  by  the  help 
of  staging ;  but  during  the  last  few  years  the  blocks 
have  been  laid  by  an  overhanging  balanced  crane  on 
each  pier,  differing  from  the  Titans  used  at  Kurrachee, 
Madras,  and  Colombo,  in  being  able  to  revolve,  as 
well  as  travelling  backwards  and  forwards.  These 
Goliaths  can  set  blocks  of  over  40  tons,  with  an 
overhang  of  75  feet.  The  converging  piers  form  a 
harbour  of  refuge,  in  front  of  the  mouth  of  the  river, 
for  vessels  overtaken  by  storms,  and  have  enabled  the 
river  channel  to  be  easily  extended  across  the  bar, 
into  deep  water,  by  dredging.  A  sufficient  width  is 
to  be  left  between  the  pier-heads  to  ensure  that  the 
flood  tide  shall  not  be  at  all  restricted  in  entering 
the  river. 

Dredging  with  large  bucket-ladder  dredgers,  upon 
a  greatly  extended  scale,  was  commenced  in  1861, 
for  the  first  two  years  with  four  dredgers,  and  after- 
wards with  six;  and  in  1866  a  maximum  quantity  of 
5,273,500  tons,  or  about  3,515,600  cubic  yards,  was 
raised  and  removed  from  the  bed  of  the  river  between 
Newcastle  and  Tynemouth,  in  one  year.  Altogether, 
the  amount  of  material  taken  out  of  the  river  channel, 
between  1861  and  the  end  of  1888,  was  54,670,000  cubic 


2 1 2  Effects  of  River  Tyne  Works. 

yards,  or  an  average  yearly  excavation  of  nearly  2 
million  cubic  yards.  By  this  means  the  depth  over  the 
bar  has  been  increased  from  6  feet  to  over  20  feet  at  low- 
water  of  spring  tides  ;  and  a  wide  channel,  with  a  mini- 
mum depth  of  20  feet  at  low-water,  has  been  obtained 
right  up  to  Newcastle,  in  place  of  the  former  shallow, 
tortuous  channel,  almost  dry  in  places  at  low-water.  The 
river  has  also  been  deepened  to  1 8  feet  below  low-water  of 
spring  tides  for  3  miles  above  Newcastle ;  and  the  deep- 
ening of  the  river  is  proposed  to  be  eventually  extended 
5f  miles  higher  up.  These  works,  together  with  some 
straight  cuts,  and  the  removal  of  a  projecting  rocky  point, 
have  entirely  transformed  the  condition  oi  the  river  in  the 
last  thirty  years  ;  so  that  vessels  of  larger  draught  can 
reach  Newcastle  at  low-water  than  could  formerly  get  up 
on  the  highest  tides  ;  and  there  is  an  ample  depth  for 
vessels  of  the  largest  class  to  go  3  miles  above  Newcastle 
at  high-water.  These  works  have  also  placed  the  Tyne  in 
the  position  of  the  third  port  of  Great  Britain  as  regards 
the  tonnage  of  its  vessels,  and  the  fifth  in  respect  of  the 
value  of  its  imports  and  exports.  A  number  of  vessels, 
also,  of  from  2000  to  4000  tons,  enter  the  river  now  which 
could  not  possibly  have  found  access  in  1861.  The  in- 
creased capacity  given  to  the  river  channel  for  the  purposes 
of  navigation  has,  moreover,  had  the  beneficial  effect  of 
reducing  the  height  of  the  river  floods,  which  formerly 
used  to  overtop  the  river  banks  and  quays  between  Wylam 
and  Newcastle,  as  the  freshwater  discharge  finds  a  much 
freer  outflow  through  the  enlarged  and  unobstructed 
channel. 

The  river  Tyne  has  been  selected  for  description 
as  illustrating  the  improvement  of  a  tidal  river  by 
dredging,  for  this  method  of  improvement:  has  been 


River  Seine  Navigation  Works.  2 1 3 

carried  out  on  the  Tyne  to  a  greater  extent  than  else- 
where ;  but  many  other  tidal  rivers  of  Great  Britain 
have  had  their  navigable  channels  deepened  consider- 
ably by  dredging,  of  which  the  Clyde  and  the  Tees 
are  notable  examples.  Dredging,  indeed,  has  become, 
within  the  last  fifty  years,  one  of  the  principal  means 
of  artificially  improving  river  channels  and  entrances 
to  ports,  and  thus  forms  a  very  powerful  agent  in  de- 
veloping trade. 

River  Seine. — The  most  important  river  of  France,  the 
Seine,  presents  a  great  contrast  to  the  Tyne,  both  in  its 
natural  condition  and  the  principles  adopted  for  its  im- 
provement. It  is  tidal  up  to  15  miles  above  Rouen  ;  and 
by  the  introduction,  in  the  non-tidal  portion  up  to  Paris, 
of  locks  and  weirs  at  nine  places  (entirely  remodelled  since 
1878)  a  minimum  depth  of  io£  feet  has  been  provided  up  to 
Paris,  226  miles  from  its  mouth.  A  permanent  navigable 
depth,  moreover,  of  6\  feet  has  been  secured  above  Paris, 
up  to  Montereau,  a  distance  of  62  miles,  by  the  erection 
of  twelve  locks  and  weirs  since  1860.  The  Seine  has  a 
basin  of  30,370  square  miles,  about  twenty-nine  times  the 
area  of  the  Tyne  basin,  and  nearly  six  times  the  size  of 
the  Thames  basin.  It  is,  accordingly,  a  comparatively 
large  river  near  its  mouth  ;  and  it  opens  into  a  wide 
estuary.  Unlike  the  Tyne,  very  little  dredging  has  been 
carried  out  in  the  tidal  Seine,  beyond  removing  some 
hard  shoals  ;  and  the  improvement  of  the  lower  portion 
of  the  tidal  river  where  very  deficient  in  depth,  between 
La  Mailleraye  and  Berville,  has  been  effected  by  restrict- 
ing its  irregular  channel  by  mounds  of  chalk  or  stone  on 
each  side.  Whereas  the  upper  portion  of  the  tidal  river, 
between  La  Mailleraye  and  Rouen,  had  an  ample  depth 


214         Training  Works  in  Seine  Estuary. 

and  stable  channel,  the  channel  below  was  unstable, 
shallow,  and  winding,  so  that  vessels  of  200  tons  had 
frequently  some  difficulty  in  getting  up  this  part  of  the 
river,  and  wrecks  often  occurred. 

Though  various  schemes  were  proposed  from  time  to 
time  for  remedying  the  perilous  condition  of  the  Seine 
estuary,  it  was  only  in  1846  that  training  works  were  com- 
menced, confining  the  river  in  a  stable,  uniform  channel 
by  solid  mounds  along  each  side,  widening  out  gradually 
towards  the  sea.  (See  page  208).  The  scour  of  the  ebbing 
current  in  the  narrowed  channel  deepened  the  channel  as 
the  works  proceeded ;  and  the  works  were  completed  down 
to  Berville  in  1870.  These  works  increased  the  minimum 
navigable  depth  to  18  feet  at  high-water  neap  tides,  and 
enabled  vessels  of  2000  tons  to  get  up  the  river ;  and  Rouen 
was  thereby  raised  to  the  position  of  the  fifth  port  of  France. 
The  training  works  have  been  consolidated  by  additions  of 
stone  and  pitching  in  the  last  few  years  (see  section,  page 
208) ;  and  various  proposals  have  been  made  to  extend 
them  to  deep  water  at  the  mouth,  about  10  miles  beyond 
their  present  termination.  Considerable  accretion,  how- 
ever, has  taken  place,  from  material  brought  in  by  the  flood 
tide  settling  down  behind  the  training  banks,  and  at  the 
sides  of  the  estuary  beyond,  owing  to  the  enfeeblement  of 
the  ebb  current  outside  the  trained  channel ;  so  that,  in  the 
interests  of  the  ports  of  Havre  and  Honfleur,  it  has  been 
determined  to  carry  out  some  experimental  investigations, 
with  a  working  model  on  a  small  scale,  with  the  view  of 
ascertaining  the  most  favourable  lines  for  the  prolongation 
of  the  training  banks  before  commencing  any  extension 
works.  Training  works,  by  concentrating  the  ebb  and  flow 
into  a  definite,  narrowed  channel, effect,  by  natural  scour, the 
deepening  which  is  produced  artificially  by  dredging  ;  but 


Dredging  and  Training  for  River  Improvement.  2 1 5 

whereas  dredging  is  very  serviceable  in  a  narrow  river,  like 
the  Tyne  or  the  Clyde,  it  could  not  produce  a  permanent, 
deep,  and  stable  channel  in  a  wide,  exposed  estuary  like 
the  Seine  without  the  assistance  of  training  works.  More- 
over, whilst  the  depth  obtained  by  dredging  requires 
periodical  maintenance,  the  deepening  by  natural  scour  is 
maintained  by  the  same  force  which  causes  it.  Dredg- 
ing, however,  can  be  used  for  increasing  the  depth  of  a 
channel  to  any  desired  extent,  or  in  proportion  to  the 
requirements  of  a  growing  trade ;  whereas  training  works 
can  only  produce  a  certain  amount  of  deepening,  depend- 
ing on  the  current,  the  nature  of  the  river  bed,  and  the 
contraction  in  width  between  the  training  banks.  The 
necessity,  also,  of  not  checking  the  tidal  ebb  and  flow  in 
a  river  renders  it  inexpedient  to  put  the  training  banks 
very  close  together,  and  therefore  limits  the  extent  to 
which  natural  scour  is  available  in  tidal  rivers.  Con- 
siderable improvements  in  depth  can  be  effected  by 
training  works  alone,  especially  in  a  river  with  a  large 
freshwater  discharge  like  the  Seine ;  and  still  more 
can  be  accomplished  by  supplementing  training  works 
by  dredging,  particularly  in  rivers  having  a  small  fresh- 
water discharge,  as,  for  instance,  in  the  works  on  the 
Clyde  below  Glasgow,  and  the  Tees  below  Middles- 
borough. 

River  Maas. — The  mouths  of  the  river  Maas  exhibit 
some  of  the  features  characteristic  of  the  mouths  of  rivers 
flowing  into  tideless  seas,  owing  probably  to  the  flatness  of 
the  country  through  which  the  outlet  channels  flow,  and 
the  small  rise  of  tide,  of  only  6£  feet,  in  the  North  Sea  on 
that  coast.  The  river  Maas,  however,  differs  from  most 
of  the  large  tideless  rivers  in  not  bringing  down  any  large 


2 1 6          River  Maas  Improvement  Works. 

quantity  of  material  in  suspension  to  deposit  at  its  mouths. 
The  position  and  depth  of  the  outlet  channels  have  varied 
from  time  to  time ;  and  some  of  the  most  direct  channels 
have  become  shallow,  owing  to  reclamations  diminishing 
their  tidal  capacity.  The  trade  of  the  Port  of  Rotterdam, 
situated  on  the  most  northern,  or  Scheur  branch  of  the 
Maas,  was  forced  gradually  to  seek  circuitous  southern 
outlets,  which  was  very  detrimental  to  its  interests ;  and, 
accordingly,  it  was  decided,  in  1862,  to  form  a  new  direct 
northern  outlet  for  the  Scheur  branch,  by  making  a  straight 
cut,  nearly  3  miles  in  length,  across  the  Hook  of  Holland 
into  the  North  Sea,  and  to  improve  the  channel  above  by 
training  works.  The  works  were  gradually  carried  out  in 
the  following  years  ;  the  river  was  trained  from  Krinpen, 
above  Rotterdam,  towards  the  sea,  with  a  gradually 
expanding  channel  ;  the  cut  was  made  across  the  Hook 
of  Holland,  in  continuation  of  the  trained  channel ;  the 
channel  was  prolonged  out  to  deep  water,  between  parallel 
jetties,  or  breakwaters,  formed  of  mattresses  of  fascines 
weighted  with  stones  ;  and  the  old  outlet  to  the  south  of 
the  Hook  of  Holland  was  closed.  Dredging  has  been 
carried  out  in  the  new  channel  to  increase  its  depth,  so 
that  vessels  of  large  size  can  now  go  up  to  Rotterdam,  the 
minimum  depth  to  be  maintained  being  23  feet  at  high- 
water.  The  improved  channel  has  greatly  increased  the 
trade  of  Rotterdam,  and  the  port  has  been  considerably 
extended  ;  and  the  remarkable  change  which  has  occurred 
in  the  general  condition  of  Rotterdam  bears  unmistak- 
able evidence  of  the  advantages  it  has  derived  from 
its  new  maritime  channel. 

River  Danube. — The  Danube  is  the  largest  river  in 
Europe;    but   though   it  has    a    basin    about   fifty-eight 


Description  of  Danube  Delta.  2  i  7 

times  the  size  of  the  Thames  basin,  it  had  a  maximum 
depth  of  only  12  feet  at  the  deepest  of  its  mouths  at  the 
most  favourable  period  ;  so  that  its  great  discharge  was 
unable  to  form  an  outlet  channel  at  all  approaching  the 
depth  at  the  mouth  of  the  Thames  at  high  tide.  The 
very  unsatisfactory  condition  of  its  outlets  was  the  re- 
sult of  the  formation  of  a  delta  at  its  mouth,  by  the 
deposit  of  the  silt  carried  in  suspension  by  the  river, 
gradually  extending  into  the  Black  Sea  which  is  devoid 
of  tidal  oscillations.  At  the  commencement  of  the  delta, 
45  miles  from  the  Black  Sea,  the  Danube,  which  has 
a  single  channel  above,  1700  feet  wide  and  50  feet  deep, 
splits  up  into  three  diverging  channels.  The  northern 
and  largest  of  these  channels  forms  a  second  delta  near 
its  outlet,  passing  into  the  Black  Sea  through  several  very 
shallow  mouths  ;  and  this  delta  advances  at  the  rate  of  a 
mile  in  about  twenty-five  years,  as  the  channel  discharges 
nearly  two-thirds  of  the  sediment-bearing  waters  of  the 
Danube.  The  central,  or  Sulina  Channel  was  selected  for 
improvement,  for,  though  the  smallest  of  the  three 
branches,  it  possesses  a  better  depth  over  the  bar  at  its 
mouth  than  the  other  two.  Moreover,  as  the  Sulina 
Channel  only  discharges  about  one-thirteenth  of  the  whole 
flow  of  the  Danube,  the  advance  of  its  delta  seawards  is 
the  least  rapid  of  the  three,  having  been  about  94  feet, 
on  the  average,  in  a  year  before  the  execution  of  the 
improvement  works. 

The  amount  of  material  brought  down  by  large  delta- 
forming  rivers  is  much  too  great  to  be  controlled  by 
dredging;  and  therefore  the  only  methods  of  affording 
the  inland  navigation  of  silt-bearing  tideless  rivers  an 
outlet  to  the  sea  consist,  either  in  narrowing  one  of  the 
mouths  by  jetties  extending  straight  out  from  the  shore 


2 1 8         Piers  at  Sulina  Mouth  of  Danube. 

towards  the  bar,  and  thus  making  the  concentrated 
current  scour  the  bar,  and  carry  the  material  in  sus- 
pension into  deeper  water,  or  in  avoiding  the  delta 
altogether,  by  forming  a  canal  connecting  the  river 
above  with  the  sea  at  a  point  beyond  the  influence  of  the 
river  mouths.  The  former  method  has  been  adopted 
for  the  Danube  and  the  Mississippi,  and  the  latter  for 
the  Rhone,  by  means  of  the  St  Louis  Canal,  constructed 
in  1863-73. 

Two  piers  were  built  out  from  the  shore  on  each  side 
of  the  Sulina  mouth,  and  carried  across  the  bar  in  a 
parallel  direction,  600  feet  apart,  into  a  depth  of  18  feet 
of  water.  These  piers  were  commenced  as  temporary 
constructions  in  1858,  and  completed  in  1861  ;  and  eventu- 
ally, when  their  results  had  been  manifested,  and  the 
Sulina  Channel  was  finally  adopted  as  the  permanent 
outlet,  they  were  strengthened  and  consolidated  in 
1868-71.  The  piers  are  composed  of  mounds  of  rubble 
stone,  surmounted  by  a  concrete  block  wall,  and  pro- 
tected on  the  outer  slopes  by  2O-ton  concrete  blocks. 
The  northern  pier  is  rather  over  a  mile  in  length ;  but 
the  southern  pier,  starting  rather  further  out,  is  some- 
what shorter. 

The  influence  of  the  increased  current  over  the  bar, 
created  by  the  piers,  was  felt  as  early  as  the  end  of  1860  ; 
and  the  floods,  instead  of  raising  the  bar  by  the  deposit 
of  the  material  brought  down  by  them  as  before,  scoured 
away  the  bar,  and  carried  the  material  in  suspension  into 
deeper  water;  and  a  minimum  depth  of  i6J  feet,  with  a 
width  of  500  feet,  was  attained  in  1861.  The  southern 
pier  was  extended,  in  1869,  out  as  far  as  the  northern 
pier;  and  in  1870  a  depth  of  22  feet  was  obtained 
over  the  bar,  where,  in  1858,  the  depth  had  only 


Improvement  of  Sulina  Mouth.  2 1 9 

averaged  about  9^  feet.  The  river,  of  course,  eventu- 
ally deposits  its  material  in  the  sea ;  but  though  a 
portion  of  this  material  is  accumulating  further  out 
in  front  of  the  mouth,  some  of  the  discharge  from 
the  river  has  been  brought  under  the  influence  of 
a  littoral  current  flowing  southwards,  which  carries 
away  a  portion  of  the  material  in  suspension  ;  so  that 
the  rate  of  the  advance  of  the  delta  in  front  of  the 
Sulina  mouth  is  only  about  half  what  it  was  previous 
to  the  works.  By  degrees,  the  material  which  is 
accumulating  in  deep  water  beyond  the  piers  will 
form  another  bar  outside,  which  will  sooner  or  later 
necessitate  an  extension  of  the  jetties  to  scour  it  away. 
Hitherto,  however,  the  piers  have  maintained  an  outlet 
channel  having  double  the  depth  which  it  formerly 
possessed. 

The  Danube,  in  a  point  of  its  course  much  higher 
up,  encounters  an  obstacle  to  navigation  of  a  totally 
different  nature,  in  the  form  of  reefs  of  limestone, 
granite,  and  other  rocks,  which  create  dangerous 
rapids,  and  render  the  passage  of  the  river  difficult 
for  vessels.  These  shoals,  known  as  the  Iron  Gates 
of  the  Danube,  are  situated  below  Orsova,  in  the 
portion  of  the  river  flowing  between  Hungary  and 
Servia,  and  are  in  course  of  removal  at  the  present 
time  by  blasting,  to  improve  the  channel  for  navi- 
gation. 

River  Mississippi.  —  Though  the  Danube  is  the 
largest  of  European  rivers,  it  appears  small  when 
compared  with  the  large  rivers  of  the  American 
Continent,  such  as  the  Amazon,  the  La  Plata, 
and  the  Mississippi.  Thus  the  Mississippi  has  a 


22O  Description  of  Mississippi  Delta. 

length  of  more  than  two  and  a  half  times  that 
of  the  Danube,  and  a  basin  four  times  the  size  of 
the  basin  of  the  Danube.  Like  the  Danube,  the 
Mississippi  brings  down  a  large  quantity  of  alluvium 
in  flood  time,  which  it  deposits  at  its  outlet,  form- 
ing a  very  extensive  delta,  stretching  out  into  the 
almost  tideless  Gulf  of  Mexico,  with  an  area  of 
12,300  square  miles.  The  material  which  the  river 
brings  down  in  flood  time  amounts  to  2800  cubic 
feet  of  solid  matter  per  second,  which  is  equiva- 
lent to  a  cube  of  about  207  yards  in  a  day,  or  more 
in  ten  hours  than  the  maximum  dredged  out  of  the 
Tyne  in  a  year.  Owing  to  the  greater  depth  of  the 
sea  in  front  of  the  Mississippi  delta,  the  average  rate 
of  advance  of  the  delta,  of  about  220  feet  in  a  year, 
is  not  much  more  than  the  advance  of  the  Danube 
delta  at  the  Kilia,  or  northern  mouths,  in  spite  of 
the  much  larger  volume  of  material  brought  down 
by  the  Mississippi.  The  Mississippi  flows  through  its 
delta,  into  the  Gulf  of  Mexico,  by  four  principal 
channels,  or  passes  as  they  are  termed,  diverging 
from  the  main  channel  about  15  miles  from  the 
Gulf.  (See page  208.)  These  passes  were  impeded  by 
shoals  at  their  starting  point,  and  by  a  bar  at  their 
outlets ;  so  that  whereas  the  river,  35  miles  above 
its  outlet,  has  on  the  average  a  depth  of  120  feet 
and  a  width  of  2470  feet,  it  afforded  a  depth  of  only 
13  feet  over  the  deepest  channel  across  the  lowest 
of  the  bars,  at  the  mouth  of  the  South-West  Pass, 
which  was  with  difficulty  increased  temporarily  by 
dredging  to  18  feet 

The   South    Pass,  discharging   only  about   one-tenth 
of  the  volume  of  the   river   flow,  was   selected    as   the 


Jetties  at  South  Pass  of  Mississippi.        221 

channel  to  be  improved,  as,  owing  to  its  smaller  size, 
the  jetty  works  required  were  less  costly  than  at  the 
South- West  Pass,  which  possessed  a  wider  channel 
and  a  better  depth  over  the  bar  at  its  outlet  The 
yearly  advance,  moreover,  of  the  delta  in  front  of 
the  South  Pass  was  less  than  in  front  of  the  other 
three  passes,  as  its  discharge,  and  consequently  the 
material  brought  down  it,  is  less.  Before  the  com- 
mencement of  the  works,  the  South  Pass  was  impeded 
by  a  shoal  at  its  upper  end,  with  a  depth  of  only 
15  feet  of  water  over  it,  and  by  a  bar  in  front  of  its 
outlet,  with  a  depth  of  only  8  feet  over  it. 

The  method  of  improvement  adopted  at  the  mouth 
of  the  South  Pass  was  similar  to  the  works  previously 
carried  out  with  success  at  the  Sulina  mouth  of  the 
Danube,  namely,  scouring  a  deeper  channel  over  the 
bar  by  the  concentration  of  the  river  current  between 
parallel  jetties  across  the  bar.  The  South  Pass  jetties, 
commenced  in  1875,  form  artificial  prolongations  of  the 
banks  of  the  channel  seawards  for  a  distance  of 
2\  miles,  placed  1000  feet  apart.  The  jetties  are 
composed  of  tiers  of  mattresses  of  interwoven  osiers, 
weighted  with  stones  along  the  inner  portions,  and 
with  large  concrete  blocks  along  the  outer  portions, 
the  blocks  at  the  outer  ends  reaching  over  260  tons  in 
weight,  to  secure  the  mattresses  against  disturbance  by 
the  waves.  (See  section, page  208.)  The  east  jetty  is  2$ 
miles  long,  and  the  west  jetty  i^  miles,  extending  to 
the  same  distance  out,  in  a  depth  of  30  feet  of  water ; 
and  they  were  completed  in  1879.  In  1877  the  channel 
over  the  bar  had  been  deepened  from  8  feet  to  20  feet, 
which  increased  to  28  feet  in  1879,  and  eventually  to 
30  feet,  with  a  width  of  70  feet,  by  the  action  of  the 


222          Deepening  of  South  Pass  by  Scour. 

natural   scour   of  the    river,    directed   and    concentrated 
by  the  jetties. 

The  shoal  at  the  upper  end  of  the  South  Pass 
was  also  deepened  by  the  scour  resulting  from  a 
contraction  of  its  entrance  by  willow  mattresses ;  but 
as  this  contraction  tended  to  divert  a  portion  of  the 
discharge  of  the  South  Pass  into  the  other  channels,  it 
became  necessary  to  reduce  the  sections  of  the  entrance 
channels  to  the  other  passes  by  sinking  willow  mattresses 
across  them,  so  that  the  South  Pass  might  continue,  in 
spite  of  its  contracted  entrance,  to  receive  its  due  propor- 
tion of  the  discharge  of  the  river.  In  this  manner  the 
channel  over  the  shoal  at  the  upper  end  of  the  South 
Pass  has  attained  a  depth  of  from  30  to  35  feet  of 
water  for  a  width  of  275  feet ;  so  that  there  is  a  regular 
navigable  channel  throughout  the  South  Pass,  having 
a  minimum  depth  of  30  feet,  where,  fifteen  years  ago,  it 
was  impeded  by  a  shoal  at  the  upper  end,  with  a  maxi- 
mum depth  of  15  feet  over  it,  and  by  a  bar  at  the 
lower  end,  with  a  depth  over  it  of  only  8  feet.  The 
contraction  of  the  outlet  of  the  South  Pass,  from  a 
width  of  2  miles  to  1000  feet,  besides  lowering  the 
bar  by  the  resulting  scour,  has  carried  the  material  in 
suspension,  formerly  deposited  on  the  bar,  into  deeper 
water,  and  within  the  influence  of  the  westerly  littoral 
current  in  front  of  the  pass.  Accordingly,  the  material 
brought  down  by  the  river  has  been  partially  carried 
away  by  the  westerly  current ;  and  the  remainder  has 
been  deposited  in  a  sufficient  depth  to  prevent  the 
accumulations  reaching  for  some  years  a  height  impeding 
navigation.  As  soon  as  the  continued  accumulations  of 
deposit  encroach  upon  the  30  feet  depth,  it  will  be 
necessary  to  prolong  the  jetties  seawards,  so  as  to  scour 


Results  of  Dredging*  Training,  and  Jetties.   223 

away  the  fresh  deposits  to  the  requisite  depth,  and  to 
drive  the  material  into  depths  where  its  accumulations 
will  not  interfere  with  the  navigable  depth  at  the  outlet 
for  another  series  of  years. 

The  above  examples  show  what  remarkable  results 
can  be  accomplished  by  dredging  and  training  works  in 
tidal  rivers  and  estuaries,  and  by  parallel  jetties  at  the 
mouths  of  tideless  rivers,  in  deepening  the  outer  channels 
for  sea-going  vessels  ;  and  they  also  afford  evidence  of 
the  great  advances  made  in  the  development  of  the 
navigable  capacities  of  rivers  within  recent  years. 


CHAPTER     XII. 

THE  WEIRS  OF  POSES  ON  THE  SEINE,  AND  OF  CHAR- 
LOTTENBURG  ON  THE  SPREE;  AND  THE  HYDRAULIC 
CANAL  LIFT  OF  LA  LOUVIERE. 

THE  improvement  of  the  Lower  Seine,  between  the 
termination  of  the  tidal  portion  at  St  Aubin  and  Paris, 
has  been  already  alluded  to  in  the  preceding  chapter. 
It  has  been  effected  by  the  ordinary  method  adopted 
upon  all  other  canalised  rivers,  namely,  by  raising  the 
water  level  of  the  river  by  means  of  barriers,  termed 
weirs,  put  across  the  channel  at  certain  places,  and 
thus  increasing  the  depth  of  water ;  whilst  the  passage 
of  vessels  at  these  weirs  is  provided  for  by  locks 
placed  at  the  side  of  the  weir,  or  in  a  small  subsidiary 
channel.  The  river  is  thereby  divided  into  a  number 
of  reaches,  with  different  water  levels  ;  and  the  vessels 
accomplish  the  change  of  level  at  each  weir  by  being 
raised  or  lowered,  on  entering  the  lock,  by  the  filling  or 
emptying  of  the  lock  chamber,  which  is  closed  at  each 
end  by  gates.  The  discharge  of  the  river  has  to  pass 
over  or  through  the  weirs  ;  and  as  the  water  level  is 
raised  by  the  weir,  it  is  important  to  provide  an 
ample  passage  for  the  river  in  flood  time,  so  that  the 
improvements  effected  for  navigation  may  not  lead 
to  increased  inundation  of  the  riparian  lands.  This 


Advantages  of  Move  able  Weirs.  225 

consideration  has  led  to  the  construction  of  moveable 
weirs,  which  keep  up  the  level  of  the  water  in  dry 
weather,  when  the  water  would  otherwise  flow  away 
leaving  an  insufficient  depth  in  places  for  navigation, 
but  can  be  removed  from  the  channel  in  flood  time, 
when  an  abundance  of  water  renders  these  barriers 
unnecessary  for  navigation,  and  only  an  impediment 
to  the  passage  of  the  flood  waters.  Various  types  of 
these  moveable  weirs  have  been  erected  across  rivers 
for  improving  their  navigable  depth,  especially  in  France, 
within  the  last  fifty  years  ;  for  only  three  such  weirs, 
of  the  simplest  modern  type,  were  erected  previous  to 
1840,  whilst  now  numerous  moveable  weirs  of  im- 
proved construction  may  be  seen  in  France,  Belgium, 
Germany,  and  Russia,  and  some  large  examples  of 
similar  weirs  in  the  United  States. 


MOVEABLE  WEIRS. 

The  simplest  form  of  moveable  weir  consists  of 
a  series  of  small  square  wooden  spars,  placed  side 
by  side,  and  resting  nearly  vertically  against  a  sill 
in  the  bed  of  the  river,  and  against  a  footbridge 
supported  on  a  row  of  wrought-iron  frames  which, 
being  hinged  at  the  bottom,  can  be  laid  flat  on  the 
bed  of  the  river  in  flood  time.  These  spars, 
sloping  slightly  upstream  towards  the  bottom,  form 
a  continuous  barrier  across  the  river  in  dry  weather, 
and  can  be  removed,  one  by  one,  by  a  man  on  the 
footbridge,  as  the  discharge  of  the  river  increases ;  and 
eventually,  when  all  the  spars  or  needles  are  removed, 
the  footbridge  taken  up,  and  the  frames  lowered,  the 


226          Various  Types  of  Moveable  Weirs. 

channel  is  left  quite  unobstructed.  These  needle 
weirs  have  been  extensively  adopted  on  the  French 
rivers ;  and  fine  examples  of  them  may  be  seen  on 
the  Meuse  in  Belgium,  and  on  the  Main  between 
Frankfort  and  the  Rhine. 

Shutter  weirs  were  for  the  first  time  introduced, 
in  1852,  on  the  Upper  Seine  above  Paris.  They 
consist  of  a  series  of  panels,  each  revolving  upon  a 
central  horizontal  axis,  supported  on  a  moveable 
iron  trestle  at  the  back  of  the  panel.  These  shutters 
form  a  continuous  weir  across  the  river ;  and  the 
discharge  of  the  river  over  them  can  be  increased  by 
turning  them  slightly  on  their  axis ;  or  they  can  be 
lowered  completely  on  to  the  bed  of  the  river,  by 
releasing  a  prop  supporting  the  trestle  of  each  panel 
or  shutter.  This  type  of  weir  has  been  used  on  the 
Upper  Seine,  the  Rhine,  and  the  Meuse  ;  it  has  been 
introduced  into  Russia,  and  has  also  found  a  home 
in  the  United  States,  on  the  Ohio  and  Great  Kanawha 
rivers. 

The  most  novel  type  of  weir  is  to  be  found  in 
the  recently  completed  weirs  of  Poses  and  Port- 
Mort,  erected  for  improving  the  navigable  condition 
of  the  Lower  Seine.  Another  very  ingenious  and 
remarkably  easily  regulated  form  of  weir,  known  as 
the  drum  weir,  was  for  a  long  time  confined  to  the 
River  Marne,  where  it  was  first  introduced  in  1857. 
This  type  of  weir  has,  however,  been  adopted  for 
closing  the  timber  passes  at  the  weirs  erected  for 
canalising  the  Main  below  Frankfort,  in  1883-86;  and 
a  drum  weir,  on  a  still  larger  scale,  was  erected  about 
the  same  time  across  the  navigable  pass  of  the 
River  Spree  at  Charlottenburg. 


Modifications  of  Weirs  on  Loiver  Seine.     227 

Poses  Weir. — The  canalisation  of  the  Seine  below 
Paris  was  only  commenced  in  1838  ;  and  the  works  then 
begun,  and  completed  in  1866,  were  merely  designed 
to  secure  a  navigable  depth  of  5^  feet,  by  the  erection 
of  seven  needle  weirs,  with  adjoining  locks  for  the 
passage  of  vessels.  On  the  termination  of  these  works, 
fresh  works  were  deemed  expedient  to  increase  the 
depth  from  5^  to  65  feet,  which  was  accomplished 
by  an  additional  weir,  and  by  raising  three  of  the 
existing  weirs.  In  1878  it  was  decided  to  increase 
the  depth  of  the  Seine  between  Rouen  and  Paris  to 
loj  feet,  so  as  to  enable  vessels  of  800  to  1000  tons, 
and  of  nearly  10  feet  draught,  to  reach  Paris.  This 
involved  the  rebuilding  of  all  the  locks,  the  recon- 
struction of  some  of  the  weirs,  and  the  modification 
of  the  others.  The  increased  height  of  the  weirs,  to 
raise  the  water  level  and  thus  augment  the  depth,  was 
in  some  cases  too  great  to  enable  the  old  system  of 
closing  the  weir  with  spars,  or  needles,  to  be  retained. 
In  two  instances,  at  Suresnes  near  Paris,  and  Port 
Villez  near  Vernon,  the  old  frame  system,  on  an  en- 
larged scale,  was  employed ;  but  the  closing  is  effected 
in  the  one  case  by  a  series  of  sliding  panels  between 
each  pair  of  frames,  and  in  the  other  case  by  hinged 
curtains  rolling  up  from  the  bottom.1  At  Poses,  however, 
the  weir  was  entirely  remodelled,  and  a  new  type  of 
weir  was  adopted.  The  principle  of  the  frame  weir, 
with  hinged  curtains  resting  against  the  frames,  has 

1  This  curtain  consists  of  a  series  of  horizontal  laths  of  wood  hinged 
together,  increasing  in  thickness  towards  the  bottom  so  as  to  sustain  the 
water  pressure  which  increases  with  the  depth.  The  curtains,  which 
resemble  somewhat  in  principle  the  flexible  iron  shutters  for  closing  shop 
windows,  are  rolled  up  from  the  bottom  by  a  pair  of  endless  chains, 
encircling  each  curtain,  wound  up  by  a  special  winch  at  the  top. 


228  Hanging  Frames  from  Bridges. 

been  retained  ;  but  the  frames,  instead  of  being  hinged 
to  a  stone  floor  in  the  bed  of  the  river,  and  lowered 
sideways,  are  hinged  at  the  top  to  an  overhead  girder 
bridge,  and  are  raised  in  pairs  upstream  (with  a  curtain 
rolled  up  upon  them),  to  a  horizontal  position  under  the 
bridge,  when  the  weir  has  to  be  removed.  By  this 
means  all  the  moveable  parts  of  the  weir  are  lifted 
entirely  out  of  the  river  during  the  winter  months, 
instead  of  being  entirely  submerged  as  in  the  case  of 
the  shutter  weirs,  or  leaving  the  frames  in  the  bed  of 
the  river  as  in  the  needle  weirs  and  other  similar  frame 
weirs.  This  new  arrangement,  however,  though  avoiding 
liability  to  injury,  and  making  the  raising  and  lowering 
of  the  frames  much  easier,  involves  the  somewhat  costly 
adjuncts  of  a  wide  overhead  bridge,  and  high  piers  at  the 
sides  of  the  navigable  passes.  The  bridge  is  necessary 
as  a  support  from  which  the  frames  can  be  hung ;  and 
it  has  to  be  wide,  to  enable  the  frames  to  be  raised  by 
chains  attached  to  each  frame  at  some  little  distance 
from  the  hinge. 

On  the  Seine,  as  on  other  continental  rivers,  the 
locks  are  submerged  during  floods,  so  that  vessels 
in  flood  time  pass  over  the  sites  of  the  moveable  weirs 
at  places  where  the  foundations  of  the  weir  are  speci- 
ally low.  As  these  navigable  passes  in  the  weirs  have 
to  be  available  for  navigation  at  all  times  when  the  weir 
is  open,  except  in  extreme  floods  when  the  naviga- 
tion is  stopped,  it  is  necessary  that  any  fixed  bridge 
over  these  passes  should  afford  an  ample  headway 
for  the  masts  of  such  vessels  as  navigate  the  riven 
Accordingly,  a  clear  height  of  i?J  feet  had  to  be 
provided  at  Poses  Weir,  across  the  navigable  passes,  be- 
tween the  highest  navigable  level  and  the  under  side  of 


Description  of  Poses  Weir.  229 

the  frames  when  raised  under  the  overhead  bridge. 
The  bridge,  therefore,  had  to  be  raised  to  a  sufficient 
height  over  the  two  navigable  passes  at  Poses  Weir  to 
secure  this  headway ;  whilst  the  bridge  over  the  rest  of 
the  weir  has  only  been  placed  high  enough  to  ensure 
that,  with  the  frames  raised  underneath,  there  may  be 
ample  clearance  in  the  highest  possible  flood. 

The  weir  at  Poses  stretches  across  a  wide  branch 
of  the  river,  only  separated  from  the  narrower  channel 
in  which  the  locks  are  situated  by  the  narrow  end  of 
an  island.  The  weir  has  seven  openings  separated  by 
masonry  piers,  13  feet  wide,  upon  which  the  girders 
carrying  the  bridge  across  these  openings  rest.  Five  of 
the  openings  have  a  width  of  99  feet;  and  the  two  navig- 
able passes  are  each  io6J  feet  wide.  The  head  of  water 
retained  by  this  weir,  or  the  difference  in  level  between 
the  upper  and  lower  reaches,  is  13  feet  at  the  ordinary 
water  level.  The  wrought-iron  frames,  composed  of  four 
vertical  pieces  braced  together,  are  38  feet  long ;  and  the 
overhead  bridge  has  a  similar  total  width.  The  curtain 
resting  against  each  frame  is  *j\  feet  wide  (see  note,  page 
227)  ;  and  it  is  rolled  up  from  the  bottom  by  two  chains 
wound  up  by  a  winch  travelling  on  a  little  footbridge 
formed  by  a  series  of  iron  flaps  hinged  to  the  back  of 
each  frame.  One  of  the  deep  passes  of  the  weir  can 
be  entirely  opened  in  five  hours,  by  rolling  up  the  four- 
teen curtains  and  raising  the  frames. 

The  navigation  at  Poses  is  provided  for,  in  ordinary 
states  of  the  river,  by  three  locks  of  different  sizes, 
placed  side  by  side,  the  largest  lock  having  a  length 
of  524  feet,  and  a  width  of  55!  feet. 

The  weir  at  Poses,  which  was  put  into  operation 
in  1885,  is  tne  largest  work  of  the  kind  hitherto  con- 


230  Improvements  of  River  Seine. 

structed.  Moreover,  the  portion  of  the  weir  at  present 
visible  does  not  give  an  adequate  conception  of  the 
magnitude  of  the  work ;  for,  besides  the  part  sub- 
merged in  the  water,  the  foundations  had  to  be  carried 
27!  feet  below  the  floor  of  the  weir;  so  that  the 
total  height  of  the  weir,  extending  across  a  width 
of  river  of  about  800  feet,  is  77  feet  from  the  bottom 
of  the  foundations  to  the  top  of  the  girders  across 
the  navigable  passes.  These  works,  together  with 
similar  works  at  Port-Mort,  the  next  weir  higher  up, 
and  other  works  of  considerably  less  magnitude,  have 
raised  the  Seine,  for  a  length  of  135  miles,  from  being 
a  river  impeded  by  numerous  shoals,  and  difficult  to 
navigate  by  small  vessels  in  dry  seasons,  into  a  river 
possessing  a  permanent  navigable  channel  of  10^  feet, 
giving  access  for  large  river  craft  right  up  to  Paris. 

Charlottenburg  Weir. — The  works  for  canalising  the 
river  Spree  at  Charlottenburg  consist  of  a  weir  across 
the  main  channel,  and  two  locks  in  a  side  channel 
separated  from  the  main  channel  by  an  island.  The 
weir  is  divided  into  five  openings  by  piers  in  the  river. 
Four  of  these  openings,  having  each  a  width  of  34^  feet, 
are  closed  by  a  series  of  vertical  wooden  panels,  about 
9  feet  high  and  7  feet  wide,  which  can  be  raised 
and  removed  in  flood  time  from  a  low  footbridge  cross- 
ing these  openings.  The  fifth  opening  has  a  width 
of  34  feet,  and  is  closed  by  a  moveable  drum  weir, 
the  largest  of  this  type  hitherto  erected.  The  foot- 
bridge traversing  the  weir  has  been  raised  over  this 
opening,  so  as  to  afford  a  clear  headway  of  not  less 
than  1 1  feet  above  the  highest  flood  level,  and  a  greater 
headway  in  the  centre.  As  this  weir  can  be  very 


DRUM   WEIR   ON    THE    SPREE    AT   CHARLOTTENBURG. 


Arrangements  of  Drum  Weir.  233 

easily  and  rapidly  lowered  or  raised,  it  can  be  used 
for  regulating  the  discharge  of  the  river,  and  thus 
adjusting  its  water  level,  or  for  the  passage  of  large 
rafts  of  timber,  for  which  purpose  these  weirs  are 
used  on  the  river  Main ;  and  the  opening  would  also  be 
available  in  flood  time  as  a  navigable  pass  for  barges. 
This  form  of  weir  consists  of  an  upper  and  lower 
paddle  revolving  upon  a  central  horizontal  axis  (see 
section,  page  232);  and  the  upper  paddle,  when 
vertical,  forms  the  weir.  The  lower  paddle  turns 
in  a  segmental  chamber  (from  the  shape  of  which, 
resembling  a  quadrant  of  a  cylinder,  the  name  of  drum, 
given  to  the  weir,  was  derived),  placed  below  the  actual 
sill  of  the  weir;  and  this  lower  paddle  controls  the 
motion  of  the  upper  paddle  for  opening  or  closing  the 
weir.  By  a  special  arrangement  of  sluice  gates  in  the 
abutment,  the  communications  between  the  [drum  and 
the  upper  and  lower  pools,  on  each  side  of  the  weir, 
can  be  alternately  opened  or  closed  more  or  less,  thus 
adjusting  the  water  pressure  on  either  side  of  the  lower 
paddle  to  any  desired  extent,  and  enabling  any  inclina- 
tion to  be  given  to  the  upper  paddle,  between  its 
almost  vertical  position  when  the  weir  is  closed  and 
its  horizontal  position  downstream  when  the  weir  is 
entirely  open.  The  weir  is,  accordingly,  under  perfect 
control,  being  worked  by  the  water  pressure  due  to  the 
head  of  water  retained  by  the  weir ;  and  the  upper 
paddle  can  not  only  be  lowered  to  any  position  in  the 
quadrant  of  the  circle  in  which  it  revolves,  but  it 
can  also  be  raised  from  the  horizontal  position  up  to 
its  full  height  against  the  rush  of  the  current  through 
the  opening.  This  form  of  weir,  therefore,  is  perfectly 
adjustable,  and  only  requires  a  few  turns  of  a  handle, 


234    Flights  of  Locks  and  Inclines  on  Canals. 

for  the  opening  or  closing  of  the  sluice  gates,  to  work 
it ;  and  the  opening  or  closing  of  the  weir  occupies 
only  a  very  few  minutes,  and  necessitates  no  footbridge 
or  other  accessories.  The  foundations,  however,  for  the 
drum  have  to  be  carried  rather  further  below  the  bed 
of  the  river  than  the  weir  is  raised  above  it,  and  the 
weir  is  therefore  costly ;  but,  on  the  other  hand,  the 
cost  of  maintenance  and  labour  in  working  are  very 
slight.  The  upper  paddle  in  the  Charlottenburg  drum 
weir  is  32}  feet  wide,  and  9§  feet  high ;  whereas  the 
upper  paddles  of  the  drum  weirs  on  the  Main  are 
39  J  feet  wide,  and  5|  feet  high. 


CANAL  LIFT  OF   LA   LOUVlfeRE. 

There  is  never  any  great  difference  of  level  in 
adjacent  reaches  of  canalised  rivers,  and  therefore  a 
single  lock  can  always  be  given  a  sufficient  rise  to 
connect  the  two  water  levels  ;  though  the  locks  have 
generally  to  be  put  closer  together  in  the  upper  part 
of  a  navigable  river,  owing  to  the  greater  inclination 
of  the  river  bed  in  the  higher  portions  of  its  valley. 
Canals,  on  the  contrary,  have  sometimes  to  cross  the 
summit  ridge  of  a  valley  dividing  two  river  basins, 
and  to  traverse  rugged  districts;  and  consequently  the 
difference  in  level  between  two  adjacent  reaches  is 
occasionally  considerable.  This  difference  is  generally 
surmounted  by  a  series  of  locks,  placed  closed  together 
in  steps  ;  but  the  passage  of  a  flight  of  locks  occupies 
a  considerable  time,  and  expends  a  good  deal  of  water. 
Inclines  have,  accordingly,  been  used,  on  which  vessels 
are  drawn  up  or  let  down  in  cradles  or  tanks,  to 


Hydra  ulic  Ca nal  L  ifts.  235 

transfer  them  from  one  reach  to  another,  where  the 
difference  of  level  is  large  and  water  scarce.  Another 
plan,  however,  of  accomplishing  the  same  object,  with 
a  saving  of  time  and  space  as  well  as  of  water,  consists 
in  raising  or  lowering  a  vessel  vertically,  in  a  trough, 
by  means  of  hydraulic  power.  This  method,  adopted 
for  the  first  time  at  Anderton,  in  Cheshire,  in  1875,  to 
connect  the  river  Weaver  with  the  Trent  and  Mersey 
Canal,  has  since  been  applied,  on  a  larger  scale,  to 
supplement  a  flight  of  five  locks  on  the  Neuffosse 
Canal  at  Fontinettes  near  St  Omer  in  France,  and 
has  also  been  resorted  to  at  La  Louviere  in  Belgium, 
on  the  canal  in  course  of  construction  for  connecting 
Mons  with  Liege. 

The  hydraulic  lift  at  La  Louviere  is  the  largest  lift 
that  has  as  yet  been  erected  ;  and  it  was  completed  in 
1888,  about  a  year  after  the  completion  of  the  slightly 
smaller  lift  at  Fontinettes.  This  lift,  like  the  two  pre- 
vious ones,  consists  of  two  parallel  wrought-iron  troughs, 
each  resting  upon  a  central  hydraulic  ram,  raised  by 
water  pressure  in  a  press  situated  below  the  bottom  of  the 
lift.  (See  illustration.}  When  the  presses  are  in  com- 
munication, the  troughs  exactly  counterbalance  one 
another,  so  that  when  one  trough  is  at  the  top  on  a 
level  with  the  upper  reach,  the  other  trough  is  at  the 
bottom  of  the  lift  and  level  with  the  lower  reach ;  and 
the  water  in  the  troughs  is  level  with  the  water  in 
the  canal.  The  ends  of  each  trough,  and  the  corre- 
sponding extremities  of  the  approach  channels  to  each 
trough,  in  the  upper  and  lower  reaches,  are  closed 
by  lifting  gates  with  watertight  joints ;  and  the  adja- 
cent gates  are  lifted  by  hydraulic  power  when  a 
communication  has  to  be  made  between  a  trough  and 


236         Louviere  Lift  on  Canal  du  Centre. 

the  canal.  The  difference  of  level  between  the  two 
canal  reaches  at  La  Louviere  is  50^  feet.  Each  trough 
is  141  feet  long,  19  feet  wide,  and  contains  about  8  feet 
depth  of  water ;  it  is  supported  by  a  hollow  cast-iron 
ram,  6  feet  in  diameter,  3^  inches  thick,  and  63!  feet 
long ;  and  the  weight  lifted,  including  trough,  water, 
and  ram,  is  1037  tons.  The  lift  is  effected,  after  the 
gates  have  been  all  lowered,  by  putting  an  additional 
10  inches  of  water  in  the  trough  at  the  top,  thereby 
overweighting  it  with  62  tons,  which  causes  it  to 
descend,  and  raises  the  lower  trough ;  whilst  any  re- 
quisite additional  assistance  in  lifting  is  furnished  by 
introducing  water  under  pressure  into  the  press  under 
the  lower  trough.  The  whole  lift  of  50^  feet  is  ac- 
complished in  two  and  a  half  minutes ;  and  a  barge 
can  be  admitted  to  each  trough,  the  lift  effected,  and 
the  barges  taken  out  of  the  troughs  again,  in  fifteen 
minutes ;  and  as  barges  of  400  tons  can  enter  the  lift, 
800  tons  can  be  passed  from  one  reach  to  the  other 
in  that  period.  The  water  pressure  is  obtained  by 
two  turbines  worked  by  the  fall  of  water  from 
the  upper  reach,  and  is  stored  up  by  an  accumulator; 
and  this  power  is  used  for  lifting  the  gates,  turning 
the  capstans,  and  working  pumps  to  keep  the  lift  pit 
dry,  as  well  as  for  lifting  the  rams  when  required.  The 
troughs  are  guided  in  their  movement  by  light  wrought- 
iron  lattice  towers  in  the  centre  and  at  each  end  ;  and 
a  man  in  a  lookout  cabin  above  the  lift  can  control 
its  working.  This  lift  is  the  first  one  of  four  lifts 
which  are  required  for  enabling  the  traffic  on  the 
canal  to  surmount  a  difference  of  level,  of  217  feet  in 
the  short  distance  of  only  5  miles,  with  a  very  small 
expenditure  of  water, 


Lift  worked  with  Ease  and  Rapidity.        237 

The  Louviere  Lift  constitutes  a  remarkable  advance 
on  the  original  Anderton  Lift ;  for,  though  the  actual 
height  of  lift  is  the  same  at  both  places,  the  length 
of  the  troughs  and  diameter  of  the  rams  at  La  Louviere 
are  double  those  at  Anderton  ;  and  this  lift  can  accom- 
modate vessels  of  four  times  the  tonnage  of  the  largest 
barges  using  the  Anderton  Lift.  The  raising  of  the 
vessel  floating  in  the  trough  is  accomplished  with 
wonderful  ease,  regularity,  and  rapidity,  with  an  ex- 
penditure of  only  about  2220  cubic  feet  of  water ;  and 
this  system,  besides  expediting  the  traffic  on  a  canal 
where  the  change  of  level  is  considerable,  enables  water 
communication  to  be  provided  across  a  country 
whose  ruggedness  would  otherwise  appear  to  preclude 
the  construction  of  a  canal. 


CHAPTER    XIII. 

THE  AMSTERDAM  SHIP  CANAL  ;  AND  THE  MANCHESTER 
SHIP  CANAL. 

THE  advantages  possessed  by  towns  situated  within 
easy  access  of  the  sea  have  been  so  fully  realised  of 
late  years,  that  several  towns  not  bordering  tidal  rivers, 
and  at  some  distance  from  the  sea-coast,  have  aimed 
at  gaining  the  same  facilities  for  trade,  by  artificial 
means,  which  towns  more  favourably  situated  possess 
naturally,  or  have  obtained  by  the  improvement  of 
their  rivers.  Thus  a  scheme  has  been  proposed  for 
converting  Paris  into  a  seaport,  by  forming  a  deep, 
straight  channel  along  the  Seine  valley,  so  as  to  bring 
the  tide  nearly  up  to  Paris.  The  inhabitants  of  Bruges 
have  for  some  time  been  urging  upon  the  Belgian 
Government  the  construction  of  a  ship  canal  to  con- 
nect Bruges  with  the  sea,  in  the  hope  of  its  restoring 
the  lost  commercial  importance  of  the  town.  A  design 
is  also  under  consideration  for  converting  Brussels  into 
a  seaport,  by  a  canal  giving  it  access  to  the  sea.  Bir- 
mingham, Sheffield,  and  other  inland  towns,  are  also 
endeavouring  to  secure  an  improved  communication 
by  water  with  seaports,  so  as  to  enable  them  to  com- 


Importance  of  Inland  Navigation.          239 

pete   on    more   equal    terms   with    their    more    favoured 
rivals. 

The   commercial    importance   of    towns   situated    at 
the   upper   limit   of   large   navigations,   such   as    Mann- 
heim on  the  Rhine,  and  the  rapid  development  of  the 
river  traffic  up  to   Frankfort   since   the   canalisation   of 
the  Main,  in   spite  of  railway  facilities   on    both  banks 
of    the    river,   sufficiently    attest    the    value    to    inland 
towns  of  good  communication  by  water  with   the   sea. 
The  ports  of  Newcastle,  Glasgow,  and  Middlesborough 
owe   their    present    prosperous   condition    to    the    large 
works    carried    out   on    their    rivers.      In    these    cases, 
however,   the   channels   existed,   though   in    a   very   de- 
fective condition,  and  were  capable  of  gradual  develop- 
ment   as    the    trade    of    the    ports   increased.      Inland 
towns,   on    the   contrary,  at  a  distance   from   any  tidal 
river,   can   only   be   converted   into   seaports  by   purely 
artificial  canal  works,  carried  out  on  a  large  scale  and 
at   a   great    cost,    which    bring    in    no    return    on    the 
capital  expended  till  after  the  final   completion  of  the 
works.     Such  works,  accordingly,  must  be  much   more 
limited   than    improvement   works    carried    out    gradu- 
ally  for   deepening    the    channel    of   tidal   rivers.      An 
important   work   of  this   description    is   the   ship   canal 
which  has  provided   the  shipping  trade  of  Amsterdam 
with  direct  access  to  the  North  Sea.     The  Manchester 
Ship   Canal,  also,  in   course  of  construction,  which  ere 
long  will  convert  Manchester  into  a  seaport,  is  a  work 
of    great   interest,   both   as    the   largest   and    most   im- 
portant canal  work  carried   out   in    Great   Britain,   and 
also   as    marking    the    revival    in    England    of    the   de- 
velopment  of  inland    navigation,   the   results   of   which 
will  be  watched  with  great  attention. 


240  Works  to  connect  Amsterdam  with  North  Sea. 


AMSTERDAM   SHIP   CANAL. 

In   olden    times    Amsterdam    was    a    port  of  great 
importance,     and      one     of     the     commercial     centres 
of   Europe.      When,  however,   the    draught    of   vessels 
increased,    the   shallow    depth   of  the    Zuider   Zee  be- 
came  inadequate ;    and    Amsterdam    was    forced,    early 
in   the   present    century,   to    seek    an    improved    outlet 
for   its   sea-going   trade.     The   shortest   route,  however, 
to    the    North    Sea,   across    Holland,   to    the    west    of 
Amsterdam,    was    considered     quite    impracticable    in 
those  days  ;   and  a  northern,   somewhat   winding   route 
was  chosen  for   the    North    Holland   Canal,  which  was 
constructed     in     1819-25,    and    connected     Amsterdam 
with  the  Texel  Roads  by  a  waterway,   52   miles  long, 
and   affording   a   depth   of  1 8£   feet.      The   continually 
increasing  draught  of  vessels,  however,  and  the  superior 
facilities  afforded  for  reaching  Antwerp  and  Rotterdam, 
again     tended     to     divert     the     shipping     trade     from 
Amsterdam,  and  obliged   Amsterdam  to  seek  a  deeper 
and    more    direct    channel    to    the    sea.      The    distance 
from   Amsterdam    to    the    North    Sea,   in    a    westerly 
direction,   is    only    15^    miles,    the    greater    portion    of 
which   consisted   of  shallow   lakes,   separated   from   the 
North    Sea   by  a  strip  of  land,  3  miles  wide,   connect- 
ing   North   and    South    Holland.      This    route,    there- 
fore, which  was  selected  for  the  Amsterdam  Ship  Canal, 
was     favourable    for    the    purpose,    as    well    as    being 
the   shortest   way    between    Amsterdam    and   the   open 
sea.       It    involved,    however,    two     difficult    problems, 
which  had  been  considered  insuperable  when  the  North 
Holland  Canal  route  was  selected  in  preference,  namely, 


SHIP        CANALS, 
SECTIONS. 

SUEZ    CANAL 


•-*i<}--7-> 


PANAMA      CANAL.. 
SECTION   IN     ETARTH.  SECTION    IN   ROCK. 


—  160-Q 


-^!c___- rrrg ~ -&#•' 

^^JS^^r 

N&^Sfcjf :  ^ !"£*$?* 


AMSTERDAM      OANAU 


88-7- 
CORINTH    CANAU.  MANCHESTER  CANAL. 


SCALE;      1 5o< 


Problems  involved  in  Amsterdam  Canal.     243 

the  maintenance  of  a  deep  entrance  across  the  flat 
sandy  beach  of  the  North  Sea,  and  the  preservation 
of  the  drainage  and  water  communication  of  the  low- 
lying  lands  bordering  the  lakes.  The  first  difficulty 
has  been  surmounted  by  sheltering  the  entrance  to 
the  canal  by  two  converging  piers,  built  out  on  the 
shore  of  the  North  Sea,  under  the  shelter  of  which 
the  entrance  channel  to  the  canal  is  maintained  by 
dredging.  The  second  difficulty  has  been  overcome 
by  shutting  off  direct  communication  with  the  sea  at 
each  end  of  the  canal,  keeping  the  canal  at  a  lower 
level  than  the  sea,  and  forming  branch  canals  connect- 
ing the  villages,  which  formerly  bordered  on  the  lake, 
with  the  ship  canal. 

The  .works  consist  of  two  piers,  forming  a  harbour 
on  the  shore  of  the  North  Sea ;  an  entrance  channel, 
leading  from  the  harbour  to  the  North  Sea  locks ;  a 
canal  excavated  through  the  land,  and  dredged  through 
the  lakes  (see  cross  section] ;  and  a  dam,  to  the  east  of 
Amsterdam,  shutting  off  the  Zuider  Zee  from  the  canal, 
in  which  a  second  set  of  locks  and  pumping  machinery 
are  situated. 

The  piers  were  constructed  of  a  wall  of  concrete 
blocks,  resting  upon  a  small  mound  of  stone,  capped 
at  the  top  by  concrete-in-mass,  and  protected  on  the 
sea  side  by  a  mound  of  large  concrete  blocks  along 
the  outer  half  of  the  piers.  These  piers,  each  about 
a  mile  in  length,  converge  from  a  width  apart  of 
nearly  4000  feet  at  the  shore  to  800  feet  at  the 
entrance,  enclosing  an  area  of  about  250  acres,  through 
which  a  central  channel,  740  feet  wide,  has  been 
dredged. 

The    North    Sea   locks   consist   of  a   large   lock    in 


244         Works  of  Amsterdam  Ship  Canal. 

the  centre,  a  small  lock  on  one  side,  and  a  sluice- 
way on  the  other  for  letting  water  out  of  the  canal 
at  low  tide.  The  large  lock  is  390  feet  long  and 
60  feet  wide,  and  the  small  lock,  227  feet  by  40  feet ; 
and  both  these  locks  and  the  sluiceway  are  provided 
with  gates  pointing  both  ways,  so  that  the  water  level 
in  the  canal  can  be  kept  at  a  uniform  level  of 
14  inches  above  low-water  in  the  North  Sea,  the  rise 
of  tide  being  5f  feet,  to  ensure  the  drainage  of  the 
low-lying  lands. 

The  canal  has  been  given  a  bottom  width  of 
88£  feet,  nearly  three  times  the  bottom  width  of  the 
North  Holland  Canal,  a  depth  of  23  feet  of  water, 
and  side  slopes  of  2  to  i.  (See  cross  section,  page  242.) 
The  material  dredged  out  for  the  canal,  through  the  lakes, 
was  deposited  at  the  sides,  forming  a  continuous  bank, 
behind  which  the  land  was  reclaimed  to  the  extent  of 
13,142  acres,  and  eventually  sold  at  about  £70  an  acre. 
These  reclaimed  lands,  and  other  low-lying  lands  for- 
merly draining  into  the  lakes,  are  drained  by  pumping 
the  surface  water  into  the  canal. 

The  dam  across  Lake  Y,  two  miles  east  of 
Amsterdam,  separating  the  canal  from  the  Zuider 
Zee,  is  4460  feet  long,  and  consists  of  an  embank- 
ment of  clay  and  sand,  deposited  on  a  series  of 
willow  mattresses  to  reduce  the  settlement  in  the 
silty  bed  of  the  lake.  The  Zuider  Zee  locks,  built 
in  Lake  Y  in  the  line  of  the  dam,  under  the  protec- 
tion of  a  temporary  circular  cofferdam,  525  feet  in 
diameter,  are  three  in  number,  the  central  one  being 
315  feet  long  and  60  feet  wide,  and  the  two  side  ones 
each  238  feet  by  47  feet.  These  locks,  and  also 
four  adjacent  sluiceways,  through  which  the  drainage 


Cost  and  Importance  of  Amsterdam  Canal.   245 

water  is  discharged  from  the  canal,  are  all  provided 
with  gates  pointing  both  ways,  for  the  same  purpose 
as  at  the  North  Sea  locks,  of  rendering  the  water 
level  in  the  canal  independent  of  the  tidal  oscillations. 
As  the  drainage  water  from  the  adjacent  lands  is 
pumped  into  the  canal,  it  is  necessary  to  remove  this 
water  in  order  to  maintain  the  canal  at  a  permanent 
level,  which  is  effected,  partly  by  letting  out  the  water 
through  the  sluice  at  each  end  during  low  tide,  and 
partly  by  pumping  machinery  creeled  close  to  the 
Zuider  Zee  locks,  at  the  northern  end  of  the  dam. 

The  canal  works  were  commenced  in  1865,  and 
completed  in  1876,  at  a  total  cost,  after  deducting 
the  amount  realised  by  the  sale  of  the  reclaimed 
lands,  of  about  £2,000,000.  There  is  a  large  and 
gradually  increasing  traffic  along  the  canal ;  and  the 
work  has  been  an  immense  benefit  to  the  trade  of 
Amsterdam,  and  also  an  advantage  to  Holland  in 
general,  which  now  possesses  two  very  accessible  sea- 
ports at  Amsterdam  and  Rotterdam,  having  direct  rail- 
way communication  with  all  parts  of  the  Continent. 


MANCHESTER   SHIP  CANAL. 

The  ship  canal,  in  course  of  construction,  between 
Manchester  and  Eastham,  on  the  Cheshire  shore  of 
the  Mersey  estuary,  has  been  designed  with  the 
object  of  enabling  large  sea-going  vessels  to  come 
right  up  to  docks  at  Manchester,  instead  of  being 
obliged  to  discharge  their  cargoes  in  the  Liverpool 
Docks  on  to  the  quays,  from  whence  they  are  carted  to 
the  railway,  and  then  forwarded  by  train  to  Manchester. 


246         Reaches  of  Manchester  Ship  Canal. 

As  the  land  rises  about  70  feet  from  the  shore  of  the 
Mersey  estuary  up  to  Manchester,  the  canal  has  had 
to  be  constructed  in  sections,  forming  level  reaches 
at  different  levels,  separated  by  locks  through  which 
the  change  of  level  will  be  accomplished.  The  total 
length  of  the  canal,  from  its  commencement  at  Eastham 
up  to  its  termination  at  the  Manchester  and  Salford 
Docks,  is  35^  miles,  divided  into  five  reaches  of  very 
different  lengths.  The  first  reach  is  tidal,  and,  skirting 
the  Cheshire  shore  of  the  estuary  from  Eastham  up  to 
a  little  beyond  Runcorn  (see  illustration],  it  passes  some- 
what inland,  and  proceeds  in  a  straight  course  to  Latch- 
ford,  a  little  past  Warrington,  where  this  reach  terminates 
at  a  set  of  locks,  its  length  being  21  miles.  The  level 
of  the  canal  is  then  raised  i6J  feet  for  the  next  reach, 
which  extends  along  the  valley  of  the  Mersey,  from 
Latchford  locks  to  Irlam  locks,  for  a  distance  of 
7j  miles.  The  level  of  the  canal  is  again  raised,  at 
the  Irlam  locks,  a  height  of  16  feet  for  the  third  reach, 
which  follows  the  valley  of  the  Irwell,  and  terminates 
at  the  Barton  locks,  with  a  length  of  only  2  miles. 
The  fourth  reach  is  raised  1 5  feet ;  and,  following 
approximately  the  course  of  the  Irwell,  and  skirting  Sal- 
ford,  it  ends  at  the  Mode  Wheel  locks,  after  traversing 
3J  miles.  The  final  reach,  above  the  Mode  Wheel 
locks,  if  miles  long,  and  raised  13  feet  higher  than  the 
previous  reach,  gives  access  to  the  docks  which  are  being 
constructed  in  the  outskirts  of  Manchester,  with  a  total 
water  area  of  114  acres.  Vessels  will,  accordingly,  rise 
6o£  feet  in  passing  through  the  four  locks,  from  the 
tidal  reach  below  Latchford  to  the  docks  at  Manchester. 
The  water  level  in  the  tidal  reach  will  be  retained  by 
tidal  locks  at  Eastham,  at  a  height  of  g\  feet  above 


$  I 


j  -5 
^ 


1 1 


l\ 


Flow  of  Tide  in  Manchester  Ship  Canal.     247 

mean  tide  level  in  the  estuary  at  that  point,  or  14^  feet 
above  the  Old  Dock  Sill  datum  at  Liverpool.1  When 
the  tide,  during  spring  tides,  rises  above  the  ordinary 
water  level  in  the  tidal  reach  of  the  canal,  which  is 
about  mean  high-water  level,  it  will  flow  in  through 
the  locks,  and  through  certain  tidal  openings  to  be 
left  in  the  embankments,  which  separate  the  canal 
from  the  estuary,  where  the  canal  crosses  small  en- 
bayments  in  the  shore  of  the  estuary.  At  the  turn 
of  the  tide,  the  lock  gates  at  Eastham  will  close,  and 
the  surplus  water  above  the  normal  level  will  flow 
out  again  through  the  tidal  openings ;  and,  if  desirable, 
the  efflux  can  be  aided  by  deep  sluices  at  the  Weaver, 
and  at  Old  Randies  higher  up.  Equinoctial  spring 
tides  rise  about  7  feet  higher  than  the  normal  water 
level  of  the  tidal  reach  of  the  canal.  The  canal  is  to 
have  a  minimum  depth  of  water  throughout  of  26  feet ; 
and  the  sills  of  the  locks  are  being  placed  2  feet 
lower,  so  that  the  depth  can  be  increased  when  re- 
quired to  28  feet.  The  canal  is  being  constructed 
with  a  minimum  bottom  width  of  120  feet  (see 
section,  page  242),  and  an  average  width  of  172  feet  at 
the  water  surface.  Above  Barton,  up  to  Manchester, 
the  bottom  width  is  increased  to  170  feet,  and  the  width 
at  the  water  level  to  230  feet ;  and  the  width  has  also 
been  increased  near  the  locks  to  facilitate  the  passage 
of  vessels.  Runcorn  Bridge,  built  several  years  ago,  for 
carrying  the  North-Western  Railway  across  the  Mersey 
at  Runcorn  Gap,  affords  a  clear  headway  of  75  feet 
above  the  normal  water  level  adopted  for  the  tidal 

1  The  Old  Dock  has  been  demolished  in  the  course  of  extensions  of  the 
docks  ;  but  the  level  of  its  sill  has  been  transferred  to  a  tide-guage  near  one 
of  the  dock  entrances,  and  this  level  is  5  feet  below  mean  tide  level  at 
Liverpool. 


248  Locks  on  Canal,  and  Shiices  across  Weaver. 

portion  of  the  canal  which  passes  under  it ;  and  the 
same  headway  is  being  given  under  the  other  fixed 
bridges  which  are  being  built  over  the  canal. 

The  approach  channel  to  Eastham  locks,  from  deep 
water  in  the  Sloyne,  is  to  be  dredged  to  a  depth  of  about 
40  feet  below  high-water  spring  tides ;  and  the  outer 
sills  of  the  locks  have  been  laid  3  feet  lower  than  the 
bottom  of  this  channel,  to  allow  for  a  future  increase 
in  depth.  There  are  three  locks  at  Eastham,  side  by 
side,  600  feet  long  by  80  feet  wide,  350  feet  by  50  feet, 
and  150  feet  by  30  feet;  and  there  are  two  sluiceways 
on  the  land  side  of  the  locks,  each  20  feet  in  width,  and 
closed  by  counterbalanced  sluice  gates,  moving  vertically 
on  free  rollers,  whereby  friction  is  reduced  to  a  minimum, 
so  that  they  are  very  easily  raised  against  a  head  of 
water.  The  locks  have  been  arranged  to  accommodate 
various  classes  of  vessels  without  excessive  waste  of 
water;  and  the  sluiceways  can  serve  either  to  assist 
in  filling  the  canal  on  a  rising  tide,  or  in  sluicing  the 
entrance  channel  at  low  tide.  (See  illustration.) 

As  the  line  of  the  canal  passes  across  the  mouth  of 
the  river  Weaver  where  it  flows  into  the  Mersey 
estuary,  the  embankment  of  the  canal  is  being  carried 
across  the  Weaver  outlet;  and  as  it  will  be  necessary 
to  provide  for  the  influx  of  the  tidal  water  into  the 
Weaver,  and  for  the  efflux  of  the  tidal  and  fresh  waters 
of  the  river  at  this  place,  ten  large  sluice  gates,  of  30  feet 
span,  with  deep  sills,  have  been  erected  in  the  embank- 
ment in  front  of  the  Weaver.  These  sluice  gates,  being 
counterbalanced  and  moving  on  free  rollers,  like  those 
at  Eastham  and  the  other  locks,  will  serve  to  regulate 
with  perfect  precision  the  flow  of  water  at  the  mouth 
of  the  Weaver.  Locks  are  also  being  constructed  at 


Bridges  and  Swing  Aqueduct  over  Canal.    249 

Weston  Point  and  Runcorn,  across  the  embankment 
of  the  canal,  to  allow  the  barges  of  existing  navigations 
and  docks  to  have  the  same  access  to  the  estuary  as 
previously.  Two  sluice  gates,  of  30  feet  span,  have  also 
been  erected,  by  the  side  of  the  Mersey,  at  Old  Randies, 
to  regulate  the  flow  into  or  out  of  the  canal.  The  groups 
of  locks  at  Latchford,  Irlam,  Barton,  and  Mode  Wheel, 
each  consist  of  a  large  lock,  600  feet  long  and  65  feet 
wide,  and  a  smaller  lock  of  350  feet  by  45  feet ;  and  sluice- 
ways are  provided  at  each  set  of  locks  for  discharging  any 
excess  of  water  coming  down  the  Mersey  and  Irwell, 
which  rivers  will  practically  be  absorbed  by  the  canal 
above  Latchford,  to  supply  it  with  water  for  locking. 

There  are  four  high-level  railway  bridges  constructed 
over  the  canal,  which  have  involved  considerable 
deviations  of  the  lines  to  attain  the  increased  eleva- 
tion required  to  afford  a  headway  of  75  feet  above 
the  water  level  of  the  canal.  Two  high-level  bridges, 
and  five  low  opening  bridges,  will  carry  the  roads 
across  the  canal;  and  all  the  bridges  will  leave  a 
minimum  width  of  120  feet  for  the  canal.  Owing 
to  the  angles  at  which  the  railways  cross  the  canal, 
the  actual  spans  of  the  bridges  are  greater  than  the 
clear  width  of  120  feet  left  for  the  canal;  and  in  one 
case  the  span  amounts  to  266  feet. 

Where  the  Bridgewater  Canal  crosses  over  the 
ship  canal  at  Barton,  at  too  low  a  level  to  provide 
the  requisite  headway  for  masted  vessels  passing  along 
the  ship  canal,  a  swing  aqueduct  is  provided,  turning 
on  a  central  pier,  and  leaving  an  opening  on  each 
side  of  90  feet  across  the  ship  canal.  This  aqueduct, 
containing  the  same  depth  of  water  as  the  Bridge- 
water  Canal,  will  enable  the  barges  on  this  canal  to 


250     Lifts,  Docks,  and  Appliances  on  Canal. 

cross  over  the  ship  canal.  A  pair  of  lifting  gates  at 
each  end  of  the  aqueduct  will  enable  the  ends  of  the 
trough,  forming  the  aqueduct,  and  the  adjoining  ends 
of  the  canal  to  be  closed,  when  the  aqueduct  has 
to  be  swung  round  a  quarter  of  a  circle  to  leave  the 
passages  on  each  side  of  the  central  pier  quite  clear 
for  masted  vessels  passing  along  the  ship  canal. 
Hydraulic  lifts,  similar  in  principle  to  the  lift  described 
in  the  last  chapter,  will  provide  communication  for 
barges  at  Barton  between  the  Bridgewater  Canal  and 
the  ship  canal. 

In  addition  to  the  docks  of  114  acres  at  Manchester, 
there  will  be  a  dock  at  Warrington  in  connection  with 
the  canal,  having  an  area  of  23  acres.  The  canal  is 
being  made  wider  at  Partington,  just  above  the  Irlam 
locks,  so  that  steamers  will  be  able  to  lie  there  at 
anchor ;  and  arrangements  are  being  made  for  the 
shipment  of  coal.  The  normal  width  of  the  canal  is 
sufficient  for  vessels  to  pass  at  any  point ;  and  by 
giving  the  canal  an  additional  width  at  any  places 
where  it  is  desired  to  establish  quays,  vessels  will  be 
able  to  lie  alongside  without  impeding  navigation,  and 
thus  facilities  for  trade  can  be  extended  along  the 
banks  of  the  canal.  Vessels  will  be  able  to  traverse 
the  whole  length  of  the  canal  in  ten  hours  ;  and  by 
the  employment  of  the  electric  light,  it  will  be  possible 
to  navigate  the  canal  by  night  as  well  as  by  day. 
The  canal  is  being  excavated  through  silt,  sand,  gravel, 
clay,  marl,  and  red  sandstone,  by  the  aid  of  nearly 
one  hundred  excavators,  or  steam  navvies,  of  various 
types ;  and  out  of  the  46  million  cubic  yards  of  ex- 
cavation required  for  the  canal  and  docks,  about 
10  millions  are  in  sandstone.  Some  of  this  stone  is 


Works,  Cost,  and  Prospects  of  Manchester  Canal.  2  5 1 

being  used  for  protecting  the  slopes  of  the  canal,  and 
the  river  slopes  of  the  embankments.  The  excavations 
generally  are  being  used  for  the  embankments  along 
the  sides  of  the  canal,  for  filling  up  hollows,  and  for 
raising  low-lying  land  bordering  the  canal.  The  side 
slopes  of  the  canal  vary,  according  to  the  strata 
traversed,  from  slopes  of  2  to  I  in  soft  material  to 
nearly  vertical  sides  in  rock.  One  cutting  near  Run- 
corn  has  a  depth  of  66  feet;  and  another  cutting  at 
Latchford  has  an  average  depth  of  55  feet  for  a  mile 
and  a  half. 

The  Manchester  Ship  Canal  was  authorised  in  1885  ; 
the  works  were  commenced  in  1887;  and  it  is  antici- 
pated that  the  works  will  be  completed  in  1892  or  1893. 
The  cost  of  the  works  has  been  estimated  at  £5, 330,000  ; 
but  a  committee  has  recently  reported  that  the  total 
expenditure  on  the  whole  undertaking,  including  the 
purchase  of  the  Bridgewater  Canal,  will  amount  to 
nearly  £13,000,000.  The  lower  portion  of  the  canal 
is  to  be  opened  for  traffic  in  1891.  This  canal  will 
afford  a  navigable  waterway,  from  the  sea  to  Man- 
chester, for  large  sea-going  vessels,  wider  and  deeper 
than  the  Amsterdam  Ship  Canal,  and  of  the  same 
depth  as  the  Suez  Canal  before  the  enlargement  works 
were  commenced,  and  a  bottom  width  48  feet  greater. 
(See  cross  sections,  page  242.)  Accordingly,  Manchester 
will  soon  possess  a  waterway  for  its  trade  superior 
to  the  one  provided  for  the  capital  of  Holland  by 
the  Dutch  Government,  and  more  convenient  than  the 
waterway  hitherto  provided  for  the  shipping  of  the 
world  through  the  Isthmus  of  Suez.  If  the  financial 
results  of  the  traffic  on  the  canal  should  realise  the 
anticipations  of  its  promoters,  a  great  stimulus  will  be 


252   Success  and  Magnitude  of  Manchester  Canal. 

afforded  to  the  prosecution  of  other  schemes  of  a  similar 
nature  ;  and,  accordingly,  the  traffic  returns  and  receipts 
of  this  canal  after  its  opening  will  be  followed  with 
great  interest  by  the  general  public,  as  well  as  by  those 
more  directly  concerned.  Manchester  will  undoubtedly 
derive  great  indirect  advantages  from  the  canal  in  any 
case ;  but  the  actual  financial  results  will  be  the  test  by 
which  this  great  navigation  undertaking  will  be  gauged. 
The  success  of  the  work,  from  an  engineering  point  of 
view,  is  assured  ;  and  though  larger  works  have  been 
carried  out,  none  of  equal  magnitude  have  been  at- 
tempted by  a  private  company  for  affording  a  single 
district  an  access  to  the  sea. 


CHAPTER    XIV. 

THE   SUEZ,    PANAMA,   NICARAGUA,   AND   CORINTH 
CANALS. 

THE  canals  described  in  the  last  chapter  have  been 
constructed  for  the  sea-going  trade  of  single  cities  and 
districts ;  but  there  are  localities  where  the  cutting 
of  a  waterway  across  an  isthmus  shortens  the  navig- 
able distance  between  remote  ports,  and  thereby 
affords  very  important  facilities  to  the  shipping  of 
the  world.  The  cutting  of  a  channel  through  the 
Isthmus  of  Suez,  by  connecting  the  Mediterranean 
and  Red  seas,  has  considerably  shortened  the  routes 
to  India,  Australia,  and  various  eastern  ports,  and 
has  enabled  vessels  to  avoid  the  circuitous  and  stormy 
voyage  round  the  Cape  of  Good  Hope.  The  Isthmus 
of  Panama  presents  a  natural  barrier  to  communica- 
tion between  the  Atlantic  and  Pacific  oceans,  forcing 
vessels  to  make  an  enormous  detour  to  the  south, 
round  Cape  Horn,  a  passage  noted  for  storms ;  and 
the  piercing  of  this  barrier  would  be  almost  as  great 
a  benefit  to  the  trade  of  the  world  as  the  Suez  Canal. 
Another  smaller  and  less  important  obstacle  is  the 
Isthmus  of  Corinth,  which  is  being  cut  through  for 
the  benefit  of  the  local  trade  of  the  Mediterranean 


254  Various  Schemes  for  Skip  Canals. 

and  Black  Sea.  Another  canal  is  in  course  of  con- 
struction across  Holstein,  to  form  a  shorter  connection 
between  the  Baltic  and  the  North  Sea,  for  the  benefit 
of  German  trade ;  and  canals  have  been  proposed 
to  be  made  across  the  peninsula  of  Florida,  across 
the  Isthmus  of  Perekop  which  connects  the  Crimea 
with  Russia,  and  through  the  shoals  between  Ceylon 
and  India,  with  the  object  of  providing  more  direct 
routes.  In  some  of  these  undertakings,  however,  the 
truth  of  the  old  proverb,  that  '  there  is  nothing  new 
under  the  sun/  is  curiously  borne  out ;  for  traces 
of  an  old  canal  were  found  in  the  Isthmus  of  Suez, 
which  is  believed  to  have  been  used  for  the  passage 
of  small  vessels  many  centuries  back.  A  canal,  also, 
across  the  Isthmus  of  Corinth  was  commenced  in  the 
time  of  Nero  ;  and  a  suggestion  was  made  for  cutting 
through  the  Isthmus  of  Panama  more  than  three  cen- 
turies ago.  It  has  been,  however,  reserved  for  the 
present  generation  to  witness  the  successful  comple- 
tion of  one  of  these  undertakings  on  a  large  scale; 
the  approaching  completion  of  another  which  the 
Romans  failed  to  carry  out ;  the  partial  execution 
of  a  third,  of  the  greatest  magnitude  and  difficulty; 
and  the  commencement  of  a  fourth,  across  the  same 
Isthmus  of  Panama,  which  its  promoters  intend  should 
supersede  the  earlier  undertaking. 


SUEZ   CANAL. 

The  advantages  of  a  communication  between  the 
Mediterranean  and  the  Red  Sea  were  so  obvious,  even 
within  the  limited  world  known  to  the  ancients,  that 


Route  of  Canal  across  Isthmus  of  Suez.      255 

Herodotus  mentions  a  proposal  for  cutting  a  channel 
through  the  Isthmus ;  and  the  work  appears  to  have 
been  actually  accomplished,  on  a  very  small  scale, 
about  twenty-five  centuries  ago,  but  eventually  allowed 
to  fall  into  decay.  When  Napoleon  took  possession 
of  Egypt,  at  the  close  of  the  last  century,  he  con- 
ceived the  idea  of  reopening  this  channel ;  but,  beyond 
some  surveys,  nothing  was  done  till,  in  1847,  a  series 
of  levellings  established  the  fact  of  the  identity  of  the 
levels  of  the  seas  on  both  sides  at  low-water,  which 
had  previously  been  supposed  to  be  different.  Soon 
after  proposals  were  made  for  the  construction  of 
a  canal,  at  a  uniform  level  without  locks,  across 
the  Isthmus,  for  large  vessels,  following  the  short- 
est route  along  the  natural  depressions  of  lakes 
Menzaleh,  Ballah,  and  Timsah,  and  the  Bitter 
Lakes ;  and  this  work  was  at  last  commenced  in 
1860.  (See  illustration) 

The  canal  starts  at  Port  Said,  on  the  Mediterranean, 
and  runs  nearly  due  south  to  Suez,  on  the  Red  Sea, 
with  only  a  slight  deviation  to  make  it  traverse  the 
Bitter  Lakes  in  its  course.  It  has  a  length  of  about 
100  miles ;  and  it  was  formed  with  a  bottom  width 
of  72  feet,  and  a  width  at  the  water  level  of  196  to 
328  feet,  according  to  the  material  traversed,  and 
a  depth  of  26  feet.  (See  cross  section,  page  242.)  The 
bottom  width,  however,  is  now  being  increased  to  an 
average  of  229^  feet,  and  the  depth  to  28  feet,  which 
will  eventually  be  carried  to  29^  feet  throughout,  to  pro- 
vide for  vessels  passing  at  any  part,  and  not  merely  at 
specially  widened  passing  places,  and  also  for  the  in- 
creased draught  of  vessels.  (See  dotted  line  on  cross 
section,  page  242.)  The  great  increase  of  traffic  has  neces- 


256  Dredging  Machinery  at  Suez  Canal  Works. 

sitated  these  widening  works ;  and  the  original  depth, 
when  reduced  by  deposit  from  erosion  of  the  banks, 
has  caused  delays  and  inconveniences  in  the  transit. 

The  excavation  for  the  first  45  miles  very  little 
exceeded  the  26  feet  of  depth  required  for  the  canal, 
as  the  surface  of  the  ground  across  lakes  Menzaleh  and 
Ballah  was  at  about  the  low-water  level  of  the  canal. 
(See  illustration?)  The  deepest  cutting  was  85  feet  to  the 
bottom  of  the  canal  ;  whilst  some  parts  of  the  depression 
of  the  Bitter  Lakes,  which  was  filled  with  water  by  the 
construction  of  the  canal,  were  at,  or  a  little  below  the 
level  of  the  bottom  of  the  canal.  The  material  ex- 
cavated was  mainly  sand  and  clay ;  but  south  of  the 
Bitter  Lakes,  some  rock  was  traversed,  especially  at 
the  Chalouf  cutting,  where  rock-cutting  rams  have  been 
employed  for  removing  the  rock  under  water  for  the 
recent  widening  of  the  canal.  (See  page  161.)  Sixty 
dredgers  were  employed  for  widening  and  deepening  the 
canal  during  its  construction  ;  and  long  shoots  were  used 
for  removing  the  dredged  material  to  form  the  banks 
at  the  sides  in  the  low  parts,  the  material  being  carried 
along  the  shoot  by  a  current  of  water  pumped  into  it. 
The  shoot,  230  feet  long,  was  attached  to  the  dredger 
at  a  considerable  height  above  the  water,  and  was 
also  supported  by  a  floating  pontoon  nearer  the  side ; 
and  it  delivered  the  material  direct  on  to  the  bank.  (See 
illustration?)  The  total  amount  of  excavation  was  about  98 
million  cubic  yards.  A  freshwater  canal,  from  the  Nile 
at  Cairo  to  Timsah,  and  then  going  nearly  parallel 
to  the  canal  to  Suez,  formed  one  of  the  principal 
auxiliary  works,  required  for  the  supply  of  fresh  water 
and  the  conveyance  of  materials.  A  harbour  was 
constructed  at  Port  Said  to  protect  the  entrance  to 


Port  Said  Harbour,  and  Cost  of  Canal.     257 

the  canal,  so  as  to  enable  a  channel  to  be  dredged 
from  deep  water  in  the  Mediterranean,  and  to  divert  the 
silt-bearing  current  issuing  from  the  Nile  delta,  which 
flows  from  the  west  along  the  coast.  The  harbour  is 
sheltered  by  two  converging  piers,  starting  from  the 
coast  on  each  side  of  the  canal  entrance,  the  eastern 
pier  being  6233  feet  long,  and  the  western  pier  9800  feet 
long,  and  projecting  considerably  in  advance  of  the  other 
to  keep  the  Nile  current  further  from  the  entrance. 
The  piers  consist  of  mounds  of  concrete  blocks, 
20  tons  in  weight,  composed  of  sand  and  cement,  as 
stone  could  not  be  procured  nearer  than  Alexandria. 
A  deep  channel  has  been  dredged  under  the  shelter  of 
the  west  pier,  and  is  being  maintained  to  deep  water 
without  difficulty  by  dredging,  in  spite  of  the  de- 
posits produced  by  storms  and  the  alluvial  current 
in  front  of  the  western  pier.  Basins  for  accom- 
modating vessels  have  been  formed  at  the  entrance 
to  the  canal.  The  outlet  of  the  canal  into  the  Gulf 
of  Suez,  at  the  head  of  the  Red  Sea,  has  been 
merely  protected  by  an  embankment  on  one  side, 
and  by  a  mole,  2900  feet  long,  on  the  other.  The 
canal  was  opened  in  1869;  and  its  total  cost  was 
about  £20,500,000. 

The  Suez  Canal  has  been  a  great  success,  both 
as  a  gigantic  engineering  work,  and  also  from  a 
financial  point  of  view  ;  and  though  the  credit  of  the 
work  is  due  to  French  engineers,  British  shipping 
mainly  uses  the  canal.  The  canal  has,  indeed,  at 
times  proved  inadequate  for  the  traffic  seeking  to  pass  ; 
the  wash  of  the  steamers  in  the  narrow  channel  erodes 
the  soft  banks ;  and  when  a  ship  runs  aground  the 

whole    traffic    is    blocked.      These    inconveniences   will, 

R 


258  Electric  Light  for  navigating  Suez  Canal. 

however,  be  in  a  great  measure  removed  when  the 
widening  works  are  completed.  The  congestion  of 
traffic  in  the  canal,  within  twenty  years  of  its  open- 
ing, has  been  to  some  extent  mitigated  by  the  in- 
troduction of  the  electric  light,  both  on  shore  and 
on  the  vessels  navigating  the  canal,  and  by  the  use 
of  luminous  buoys,  so  that  the  navigation  can  now 
be  conducted  safely  during  the  night.  The  capacity 
of  the  canal  for  traffic  has  been  thereby  nearly 
doubled ;  and  the  delays  involved  in  the  passage  of 
the  canal  have  been  greatly  reduced,  so  that  vessels 
are  now  able  to  accomplish  the  transit  in  22\  hours 
on  the  average. 


PANAMA  CANAL. 

The  commencement  of  an  undertaking  for  connect- 
ing the  Atlantic  and  Pacific  oceans,  through  the 
Isthmus  of  Panama,  was  a  natural  result  of  the  success 
achieved  by  the  Suez  Canal.  Various  sites  have  been 
proposed  from  time  to  time  for  the  construction  of 
a  canal  across  the  Isthmus,  the  most  northern  being 
the  Tehuantepec  route,  at  a  comparatively  broad  part 
of  the  Isthmus,  and  the  most  southern  the  Atrato 
route,  following  for  some  distance  the  course  of  the 
Atrato  River.  The  site  eventually  selected,  in  1879,  f°r 
the  construction  of  a  canal  was  at  the  narrowest  part 
of  the  Isthmus,  and  where  the  central  ridge  is  the 
lowest,  known  as  the  Panama  route,  nearly  following 
the  course  of  the  Panama  Railway.  It  was  the  only 
scheme  that  did  not  necessarily  involve  a  tunnel  or 
locks.  The  length  of  the  route  between  Colon  on  the 


Route  and  Difficulties  of  Panama  Canal.     259 

Atlantic,  and  Panama  on  the  Pacific,  is  46  miles,  not 
quite  half  the  length  of  the  Suez  Canal ;  but  a  tide- 
level  canal  involved  a  cutting  across  the  Cordilleras, 
at  the  Culebra  Pass,  nearly  300  feet  deep,  mainly 
through  rock.  The  section  of  the  canal  was  designed 
on  the  lines  of  the  Suez  Canal,  with  a  bottom  width 
of  72  feet,  and  a  depth  of  water  of  27  feet,  except  in 
the  central  rock  cutting,  where  the  width  was  to  be 
increased  to  /8f  feet  on  account  of  the  nearly  vertical 
sides,  and  the  depth  to  29^  feet.  (See  cross  sections, 
page  242.) 

The  work  was  commenced  in  1882,  and  was  carried 
on  with  dredgers  at  each  extremity,  and  with  numer- 
ous excavators  in  the  other  portions.  The  difficulties 
and  expenses,  however,  of  the  undertaking  had  been 
greatly  under-estimated.  The  climate  proved  excep- 
tionally unhealthy,  especially  when  the  soil  began  to  be 
turned  up  by  the  excavations.  The  actual  cost  of  the 
excavation  was  much  greater  than  originally  esti- 
mated ;  and  the  total  amount  of  excavation  required 
to  form  a  level  canal,  which  had  originally  been  esti- 
mated at  100  million  cubic  yards,  was  subsequently 
computed,  on  more  exact  data,  at  176^  million  cubic 
yards.  The  preliminary  works  were  also  very  ex- 
tensive and  costly ;  and  difficulties  were  experienced, 
after  a  time,  in  raising  the  funds  for  carrying 
on  the  works,  even  when  shares  were  offered  at 
a  very  great  discount.  Eventually,  in  1887,  the 
capital  at  the  disposal  of  the  company  had  nearly 
come  to  an  end  ;  whilst  only  a  little  more  than  one- 
fifth  of  the  excavation  had  been  completed.  The 
greatest  progress  had  naturally  been  made  at  the 
two  end  sections  of  the  canal :  the  canal  had  been 


260  Progress,  Plant,  and  Cost  of  Panama  Canal. 

opened  up  to  the  tenth  mile  from  Colon,  and  there 
only  remained  about  two-fifths  of  the  excavation  to 
be  accomplished  in  this  first  section  of  i6J  miles 
towards  the  end  of  1887;  and  one-third  of  the  ex- 
cavation had  been  done  in  the  last  section  at  the 
Panama  end,  lof  miles  long.  In  the  remaining 
19  miles  however,  a  very  small  proportion  of  the 
excavation  had  been  carried  out,  especially  in  the  deep 
cutting  at  Culebra,  where  constant  slips  occurred 
owing  to  the  treacherous  nature  of  the  material 
overlying  the  rock,  under  the  influence  of  tropical 
rains.  Some  idea  of  the  work  that  was  being  carried 
out  in  1887  may  be  gathered  from  the  fact  that 
seventy-two  excavators,  twenty-four  dredgers,  and  a 
number  of  locomotives,  waggons,  and  other  appli- 
ances, were  in  operation.  At  that  period  it  was 
determined  to  expedite  the  work,  and  reduce  the 
cost  of  completing  the  canal,  by  introducing  locks, 
and  thus  diminish  the  remaining  amount  of  exca- 
vation by  85  million  cubic  yards ;  though  the  esti- 
mated cost,  even  with  this  modification,  had  increased 
from  £33,500,000  to  £65,500,000.  It  was  arranged 
to  place  four  locks  on  each  slope,  with  from  26^  to 
36J  feet  differences  in  the  level  of  adjoining  reaches ; 
and  the  summit  level  was  to  be  125  feet  above  sea 
level  in  the  Atlantic.  The  financial  embarrassments, 
however,  of  the  company  have  prevented  the  carry- 
ing out  of  this  scheme  for  completing  the  canal ;  and 
the  works  are  at  present  at  a  standstill,  in  a  very 
unfinished  state.  It  will  be  unfortunate  if  all  the 
executed  work,  and  the  money  expended,  should 
turn  out  to  have  been  absolutely  fruitless.  If  the 
Panama  route  was  the  only  route  deemed  practic- 


Panama  Canal  and  Nicaragua  Canal.        261 

able  for  connecting  the  two  oceans,  it  is  fairly  certain 
that  the  unfinished  enterprise  would  be  eventually 
purchased,  at  a  low  price,  by  some  company  or  syndi- 
cate capable  of  bringing  the  works  to  a  satis- 
factory termination.  The  Americans,  however,  who 
are  the  nation  that  would  most  profit  by  the  pro- 
posed waterway,  have  always  stood  aloof  from  the 
Panama  scheme,  and  have  in  the  end  given  the 
preference  to  the  Nicaragua  route  over  other  alter- 
native schemes. 


NICARAGUA   CANAL. 

Numerous  explorations  of  the  Isthmus  of  Panama 
have  been  made  by  American  engineers,  with  the  view 
of  discovering  the  most  feasible  route  for  a  canal, 
which  would  be  of  such  inestimable  value  to  the  United 
States  in  providing  communication  by  water  between 
their  eastern  and  western  coasts.  The  result  of  a  series 
of  surveys,  instituted  by  the  Government  between  1870 
and  1876,  was  a  report  to  the  President  in  favour  of 
the  Nicaragua  route  as  the  most  practicable  and  con- 
venient site  for  a  canal.  A  concession  was  granted  by 
the  Nicaraguan  Government  to  an  American  company 
for  the  construction  of  a  canal  some  years  ago ;  and 
another  concession  was  granted  in  1885  to  a  second 
company,  who  have  endeavoured  to  establish  their 
claims  to  the  sole  right  of  constructing  the  canal  by 
actually  commencing  works  on  the  Atlantic  side, 
at  Greytown,  in  1889.  Careful  surveys  of  the 
site  have  been  made  since  1876,  so  as  to  locate 
exactly  the  line  of  the  canal.  The  site  is  nearer 


262  Design  of  Nicaragua  Canal. 

the  United  States  than  the  other  possible  routes, 
with  the  sole  exception  of  the  Tehuantepec  route 
in  Mexico,  which,  like  the  Nicaragua  route,  would 
have  to  traverse  a  comparatively  broad  part  of 
the  Isthmus,  without  the  advantage  of  a  lake  in  its 
course. 

Both  the  American  schemes  are  similar  in  general 
principles,  though  differing  in  details.  The  canal,  as 
designed,  is  to  start  from  Greytown,  or  near  it,  on  the 
Atlantic  ;  then,  rising  by  locks,  it  is  to  follow  the  valley 
of  the  San  Juan  River,  which  is  to  be  dammed  up 
so  as  to  form  a  lake  navigation.  Lake  Nicaragua  is 
to  be  the  summit  level  of  the  canal,  which  will,  after 
leaving  the  lake,  descend  by  locks  to  Brito,  on  the 
Pacific.  The  length  of  the  canal,  according  to  the 
design  actually  commenced,  will  be  169^  miles,  of 
which  56^  miles  is  through  Lake  Nicaragua,  with  a 
water  level  about  no  feet  above  sea  level.  The 
summit  level  is  proposed  to  be  reached  by  three 
locks  on  each  side ;  and  the  locks  are  to  commence, 
on  the  Atlantic  side,  about  9^  miles  from  Greytown, 
being  comprised  in  the  next  4f  miles,  from  which 
point  the  canal  will  mainly  pass  through  basins 
enclosed  by  embankments,  and  formed  by  the  dam- 
ming up  of  the  San  Juan  River,  till  Lake  Nicaragua 
is  reached,  the  total  distance  between  Greytown  and 
Lake  Nicaragua  being  nearly  96  miles.  The  slope  on 
the  Pacific  side  of  the  central  ridge  is  much  steeper 
than  the  other,  as  at  Panama ;  so  that  the  distance 
from  the  western  end  of  the  lake  portion  of  the  canal 
to  the  ocean  is  only  17  miles,  of  which  5|  miles  are 
to  be  carried  through  a  basin  formed  by  an  embank- 
ment, and  the  remainder  of  the  distance  is  to  be 


Harbours,  Navigation,  and  Cost  of  Canal.    263 

excavated    for    the    canal.      The    locks   on    this    slope 
are   to   be   comprised    in    the   last  2\  miles.     Harbours 
are  to    be    formed    at    Greytown    and    Brito,   the   two 
extremities   of   the   canal.     The   breakwater   to   protect 
the   harbour   at    Greytown    from    the    accumulations   of 
deposit,  to   which   it   is   exposed   by   the   action    of  the 
waves,   has   been    already  commenced.     Altogether,  out 
of    the     169^    miles    of    navigation    by    this    route,   as 
designed,    142!   miles   will   be   free   navigation  by  lake, 
basin,  and    river,   and    only   26f   miles   in    actual  canal. 
A  free  waterway,    besides   obviating   large   excavations, 
enables  vessels  to    travel  at  a  greater   speed  than    in  a 
restricted  canal,  and   constitutes   one  of  the  special  ad- 
vantages  of   this    scheme,    especially   across   so   wide   a 
part   of    the    Isthmus.     The   estimated    time   of    transit 
by    steamer     is    twenty-eight     hours.       The    estimated 
cost    of   the   works,    exclusive    of    all    other    incidental 
charges   and    expenses,   is   £1 8,000,000.     It   remains   to 
be    seen    whether    this    scheme   will   be    able   to    avoid 
the   troubles    which   have    overwhelmed    its   predecessor 
on    the  Isthmus ;   whether  the   capital   required    will   be 
forthcoming ;     and    whether     this    work,     unlike    other 
similar   gigantic   undertakings,  will   be   accomplished  at 
the    estimated    cost,   and    within    the    limited    period    of 
seven    years   from    its    commencement.      It    would    be 
impossible    to    form    a   reliable  opinion   as   to   the   pro- 
spects   of  the    scheme,   without    the    most  ample    infor- 
mation    and     investigations ;     but    whatever     fate     the 
future    may  have   in   store   for   this   undertaking,  which 
has.  the    advantage    of  a   comparatively   small    amount 
of    excavation,    but    the    disadvantage    of   a    bad    site 
for   a  harbour   at    Greytown,   it   is    fairly   certain    that, 
sooner     or     later,    the    problem    will     be     solved,    and 


264          Early  History  of  Corinth  Canal. 

the    two    oceans    united   by   a   waterway   piercing    the 
barrier  at  present  offered  to  navigation  by  the  Isthmus. 


CORINTH   CANAL. 

The  vessels  which  run  between  the  Mediterranean 
ports  of  Spain,  France,  Italy,  and  Austria,  and  Greece, 
Turkey,  Asia  Minor,  the  Black  Sea,  and  the  Danube, 
have  to  make  a  stormy  detour  round  Cape  Matapan, 
and  will  obtain  a  shorter  and  calmer  voyage  in 
traversing  the  Corinth  Canal.  The  Isthmus  of  Corinth 
was  a  very  serious  barrier  to  navigation  in  early 
times,  when  Italy,  Greece,  and  Asia  Minor  formed 
the  most  important  part  of  the  civilised  world,  and 
vessels  were  small,  and  sea  voyages  slow.  Accord- 
ingly, proposals  to  cut  a  canal  across  it  naturally 
originated  some  centuries  before  the  Christian  era ; 
but  the  only  work  actually  commenced  appears  to 
have  been  that  undertaken  in  the  reign  of  Nero, 
which  terminated  with  his  death ;  and  the  trial  pits 
and  traces  of  Nero's  canal  were  visible  when  the  sur- 
veys were  made  for  the  ship  canal  in  course  of  con- 
struction. The  canal,  in  fact,  follows  the  line  of  cutting 
commenced  by  Nero ;  and  the  old  trial  pits  were  re- 
lied on  for  indicating  the  nature  of  the  strata  to  be 
traversed. 

The  canal  is  being  made  in  a  straight  line  across  the 
Isthmus ;  and  its  length  is  about  100  yards  short  of 
4  miles.  This  short  length,  combined  with  easy  access, 
a  convenient  locality,  and  a  healthy  climate,  makes  the 
Corinth  Canal  a  much  less  arduous  task  than  the  un- 
dertakings previously  described  in  the  present  chapter. 
The  depth  of  cutting,  however,  to  the  bottom 


Works  and  Increased  Cost  of  Corinth  Canal.   265 

of  the  canal  reaches  a  maximum  of  285  feet,  whilst 
the  mean  depth,  for  a  length  of  2f  miles,  is  190  feet ; 
so  that  in  this  respect  it  nearly  equals  the  greatest 
depth  of  the  original  design  of  the  Panama  Canal,  and  is 
more  than  three  times  the  greatest  depth  of  cutting  on 
the  Suez  Canal.  Nevertheless,  the  slopes  of  the  rocky 
portion  of  the  cutting  were  designed  to  be  I  in  10,  greatly 
reducing  the  amount  of  excavation  compared  with  that 
which  would  have  been  needed  in  soft  soil.  The 
canal  is  being  formed  with  the  same  bottom  width  of 
72  feet,  and  depth  of  26  feet  of  water,  as  the  original 
Suez  Canal  (see  cross  section,  page  242) ;  but  as  the 
slopes  in  rock  are  only  I  in  10,  the  width  at  the  water 
level  and  the  cross  section  of  the  waterway  are  con- 
siderably less,  so  that  the  resistance  to  the  passage  of 
vessels  will  be  greater,  and  the  wash  along  the  banks 
more  powerful. 

The  works  were  commenced  in  1882;  but  as  the 
cuttings  were  opened  out,  it  became  evident  that  the 
nature  of  the  strata  had  not  been  accurately  ascertained, 
for  numerous  faults  were  discovered,  due,  doubtless,  to 
volcanic  disturbances  ;  so  that  the  sides  could  not  in 
places  stand  at  the  intended  slopes,  and  slips  occurred. 
Eventually  it  was  decided,  in  1887,  to  modify  the  slopes 
in  certain  parts,  and  to  protect  the  sides  of  the  canal 
against  erosion  by  masonry,  and  to  pave  the  slopes 
in  places  with  stone.  This  involved  an  increase  in  the 
amount  of  excavation,  from  12,865,000  cubic  yards,  to 
14  or  15  million  cubic  yards,  and  an  estimated  ad- 
dition to  the  cost  of  the  works  of  about  £600,000. 
During  1888  the  works  were  continued  upon  this 
new  basis,  the  Societe  du  Comptoir  d'Escompte  of  Paris 
providing  the  funds.  On  the  collapse,  however,  of 


266  Difficulties,  and  Works  of  Corinth  Canal. 

this  company,  in  1889,  the  works  were  stopped  for 
want  of  money ;  and  the  Canal  Company  having  gone 
into  liquidation,  the  canal  passed  into  the  hands  of 
a  new  company,  who  have  let  the  work  to  a  new 
contractor ;  and  the  time  of  completion,  originally  fixed 
for  1888,  has  been  extended  to  1894.  The  excavation 
remaining  to  be  done  at  the  time  of  the  liquidation, 
in  1889,  was  3,156,500  cubic  yards,  so  that  only  a  com- 
paratively small  proportion  of  the  work  remained  to 
be  accomplished ;  and  the  fresh  energy  imparted  by 
the  reconstitution  of  the  company,  and  the  extension 
of  time,  ought  to  suffice  to  complete  the  work.  As 
deep  water  is  found  only  about  200  to  300  yards  from 
each  end,  a  sheltering  harbour  at  each  outlet,  and  a 
channel  formed  by  dredging,  lead  the  canal  into  the 
open  sea.  Two  converging  rubble  mound  breakwaters, 
1310,  and  1640  feet  long  respectively,  with  an  entrance 
between  their  ends,  262  feet  wide,  enclose  the  harbour 
in  the  Gulf  of  Corinth  ;  whilst  a  single  breakwater  on 
the  northern  side  of  the  canal  entrance,  in  the  Gulf  of 
Athens,  affords  adequate  protection  at  that  end.  Only 
one  metal  bridge,  having  a  span  of  262  feet,  and  a 
clear  height  of  141  feet  above  the  water  level  of  the 
canal,  will  connect  the  Morea  with  the  mainland,  and 
serve  both  for  the  railway  and  the  road  traffic. 

Isthmian  canals  are  the  most  important  engineering 
works  that  can  be  carried  out ;  for  whilst  railways, 
bridges,  and  tunnels,  afford  means  of  communication 
between  districts,  and  even  countries,  these  canals 
modify  the  navigable  highways  of  the  trade  of  the 
world,  and  shorten  the  distances  between  remote  por- 
tions of  the  globe.  The  Suez  Canal,  in  realising  the 
dreams  of  past  ages,  and  by  the  rapid  development 


Uncertainties  attending  Ship  Canal  Works.   267 

of  its  traffic,  gave  a  great  impetus  to  similar  schemes, 
which  the  collapse  of  the  Panama  Canal,  in  the  middle 
of  its  execution,  and  the  financial  difficulties  of  the 
Corinth  Canal,  have  tended  to  restrain ;  though  the 
initiation  of  the  Nicaragua  Canal  indicates  that  faith 
in  the  financial  success  of  such  enterprises,  under 
difficult  conditions,  has  not  been  abandoned.  The 
difficulties  naturally  attending  such  gigantic  works  are 
enhanced  by  the  immense  sums  that  have  to  be  raised, 
without  any  prospect  of  a  return  till  after  the  com- 
pletion of  the  works,  rendering  it  necessary  to  raise 
portions  of  the  capital  on  very  onerous  conditions, 
after  the  enthusiasm  of  the  first  starting  of  the  concern 
has  subsided,  and  the  funds  of  sanguine  promoters 
have  become  exhausted.  Moreover,  whilst  the  actual 
cost  of  vast  works  of  this  nature,  extending  over  some 
years,  cannot  be  determined  with  certainty,  depending 
upon  somewhat  unknown  conditions  of  soil,  supply  of 
labour,  and  climate,  neither  can  the  actual  trade  that  a 
new  waterway  will  attract,  under  novel  conditions,  be 
predicted  with  precision.  Whatever  uncertainties,  how- 
ever, may  attend  the  financial  prospects  of  such  enter- 
prises, works  which  shorten  and  facilitate  the  routes  for 
navigation  confer  important  benefits  on  the  world  at 
large. 

Ship  Railways. — It  might  be  supposed  that  canals 
across  isthmuses  were  quite  secure  from  the  competi- 
tion of  railways,  which,  both  in  England  and  the 
United  States,  has  proved  so  very  detrimental  to  the 
traffic  on  inland  canals.  In  ancient  times,  the  Greeks 
used  to  drag  their  triremes  across  the  Isthmus  of 
Corinth  on  inclined  ways  of  polished  granite,  with 


268   Tehuantepec  and  Chignecto  Ship  Railways. 

the  aid  of  cribs  and  rollers ;  and  inclines,  provided 
with  rails,  are  used  in  Great  Britain,  Germany,  and 
the  United  States,  for  enabling  vessels  to  surmount 
considerable  differences  of  level  between  adjacent 
reaches  of  a  canal,  effecting  an  economy  of  time  and 
water  as  compared  with  a  flight  of  locks.  An  exten- 
sion of  this  system  of  inclines  was,  however,  proposed 
some  years  ago,  in  the  form  of  a  ship  railway  across 
the  Isthmus  of  Panama,  at  Tehuantepec,  where  the 
width  is  144  miles ;  and  the  vessels  were  to  be  bodily 
lifted  out  of  the  water  on  one  side,  and  carried  on 
suitable  trucks,  running  on  rails  and  drawn  by  several 
locomotives,  to  the  ocean  on  the  other  side.  This 
project  appears  to  have  been  dropped  on  the  death 
of  its  designer,  Captain  Eads,  the  engineer  of  the 
St  Louis  Bridge  and  of  the  Mississippi  delta  works. 
The  system,  however,  has  been  adopted  for  trans- 
porting vessels  across  a  narrow  neck  of  land,  15  miles 
in  width,  connecting  Nova  Scotia  with  New  Brunswick 
on  the  mainland  of  Canada,  between  Chignecto  Bay, 
an  inlet  from  the  Gulf  of  Fundy,  and  Bay  Verte  in 
the  Gulf  of  St  Lawrence.  This  Chignecto  Ship 
Railway  is  in  course  of  construction,  and  approaching 
completion  ;  and  it  will  carry  vessels  of  from  1000  to 
2000  tons,  in  cradles  supported  on  trucks  running  on 
two  lines  of  rails,  18  feet  apart,  and  drawn  by  loco- 
motives. Hydraulic  lifts  will  raise  the  vessels  from 
the  dock,  at  each  end,  on  to  the  railway ;  and  the 
transit  is  expected  to  be  effected  in  two  hours. 
This  railway  will  shorten  the  voyage  between  the  ports 
of  New  England  and  those  of  Prince  Edward's  Island 
and  the  St  Lawrence  by  from  500  to  600  miles  of 
stormy  sea.  This  work  is  intended  to  accommodate 


Object  of  Chignecto  Ship  Railway.         269 

coasting  vessels,  and  has  therefore  not  been  made 
available  for  the  largest  class  of  ships;  but  it  will 
inaugurate  a  novel  method  of  shortening  the  routes 
for  sea-going  traffic. 


CHAPTER  XV. 

THE  MANCHESTER  WATERWORKS  ;  AND  THE 
VYRNWY  DAM  AND  LAKE. 

HITHERTO  engineering  works  for  facilitating  com- 
munication and  trade  have  alone  been  considered  ;  but 
the  labours  of  the  engineer  are  not  confined  within 
even  these  very  comprehensive  limits,  for  the  sanitary 
requirements  of  cities  and  towns  are  entrusted  to  his 
care.  The  most  urgent  want  of  masses  of  people, 
crowded  into  large  towns,  is  an  ample  supply  of  pure 
water ;  for  water  is  not  only  one  of  the  first  necessaries 
of  life,  and  essential  for  health  and  cleanliness,  but 
it  is  also  a  very  common  and  insidious  vehicle  for  the 
spread  of  disease  when  in  a  polluted  state.  Unfor- 
tunately, impurities  in  water  are  not  generally  of  such 
a  palpable  kind  as  to  be  readily  detected  by  the 
senses  ;  and  some  waters,  which  to  all  appearance  are 
pure  from  their  bright  and  sparkling  qualities,  contain 
most  deadly  germs  of  disease  ;  whilst  rain  water,  which 
is  the  purest  water  obtainable,  being  distilled  by  the 
sun,  is  not  very  palatable  when  unaerated,  and,  from 
its  very  purity,  readily  absorbs  any  soluble  salts  or 
impurities  with  which  it  may  come  in  contact.  Ac- 
cordingly, the  only  method  of  securing  a  pure  supply 


Sources  of  Water  Supply  for  Towns.        271 

is  to  gather  the  water  from  the  purest  sources  avail- 
able, and  to  keep  it,  as  far  as  possible,  free  from  con- 
tamination till  it  reaches  the  consumer. 

The  sources  of  water  supply  are  tanks,  in  which 
the  rain  water  is  collected  as  it  falls ;  springs,  which 
are  the  outlets  of  natural  underground  reservoirs ; 
streams,  and  rivers ;  and  wells,  from  which  the  under- 
ground waters  are  brought  to  the  surface.  Tanks  are 
unsuitable  for  a  large  and  constant  supply ;  springs 
and  wells  are  often  used  for  moderate  supplies,  or 
as  supplementary  sources  of  supply  for  large  towns  ; 
but  rivers  and  mountain  streams  are  the  sources  from 
which  the  largest  supplies  are  derived.  Water  from 
springs  and  deep  wells  is  generally  uncontaminated, 
having  filtered  through  a  large  thickness  of  soil,  and 
being  removed  from  contact  with  impurities ;  but  it 
frequently  contains  considerable  quantities  of  inorganic 
salts  in  solution,  chiefly  of  lime  and  iron,  collected  in 
its  underground  flow,  which  constitute  the  hardness  of 
water,  and  though  quite  innocuous  as  regards  health, 
are  bad  for  washing  and  manufactures.  Waters  of 
this  kind  are  supplied  to  London  by  the  New  River 
Company,  from  springs  issuing  from  the  chalk  at 
Amwell  and  Chadwell,  in  Hertfordshire,  and  by  the 
Kent  Waterworks  Company  from  deep  wells  in  the 
chalk  to  the  east  of  London.  River  water  is  liable 
to  contamination  in  passing  towns  and  villages,  though 
the  impurities  thus  introduced  are  to  some  extent 
rendered  innocuous  by  contact  with  the  air  in  the  flow 
of  the  river.  This  water,  however,  is  much  less  liable 
to  be  impregnated  with  salts,  except  where,  as  in  the 
case  of  the  Thames,  the  river  is  partly  fed  by  springs. 
Water  from  the  Thames,  which  supplies  a  large  part  of 


272     Reservoirs  for  Water  Supply  in  Valleys. 

London,  though  harder  from  this  cause  than  many 
other  river  waters,  is  much  softer  than  the  water 
derived  wholly  from  chalk  springs  and  wells  ;  but,  on 
the  other  hand,  it  is  less  satisfactory  as  regards  the 
presence  of  other  impurities  of  an  organic  nature,  from 
which  the  other  waters  are  wholly  free. 

The  purest  water  is  derived  from  streams  drain- 
ing mountainous,  uninhabited  districts,  composed  solely 
of  rain  water  flowing  rapidly  off  the  steep,  rocky, 
impermeable  mountain  slopes,  subject  only  occasionally 
in  flood  time  to  a  slight  discoloration  by  peat,  and 
turbidity  from  earthy  matters  in  suspension.  These 
streams,  however,  have  a  very  variable  flow,  being 
almost  dried  up  when  evaporation  is  active  in  the 
summer  time  and  there  is  little  rain,  and  becoming 
rushing  torrents  during  a  rainy  winter.  As  a  water 
supply  for  towns  must  be  constant  throughout  the 
year,  and  more  water  is  required  in  the  summer,  when 
the  streams  are  liable  to  be  dry,  than  in  the  winter, 
when  there  is  an  abundant  flow,  mountain  streams 
can  only  be  made  available  for  this  purpose  by  im- 
pounding a  sufficient  quantity  of  the  surplus  winter 
flow,  to  make  up  for  the  deficiency  in  the  summer 
months.  This  is  effected  by  putting  a  watertight  barrier 
or  dam  across  a  narrow  part  of  a  mountain  valley, 
and  thus  arresting  the  flow  of  the  stream  till  it  forms 
a  lake  above  the  dam,  providing  a  reservoir  of 
water  which  can  be  drawn  upon  in  times  of  drought. 
These  dams,  composed  of  an  earthen  embankment,  hav- 
ing a  considerable  width,  or  a  masonry  wall  of  great 
strength  and  solidity,  constitute  the  largest  works 
undertaken  for  water  supply,  and  convert  portions 
of  mountain  valleys  into  extensive  lakes.  Occasion- 


Reservoirs  for  Manchester  Water  Supply.   273 

ally  natural  lakes  can  be  utilised  as  reservoirs  for  water 
supply,  by  merely  forming  a  conduit  from  the  lake 
to  the  town  to  be  supplied  at  a  lower  level.  Thus 
Glasgow  is  supplied  with  an  abundance  of  the  purest 
water  from  Loch  Katrine  ;  and  Thirlmere  is  to  afford 
Manchester  an  additional  water  supply ;  whilst  Bala 
Lake  was  suggested  many  years  ago  as  a  suitable  source 
for  an  abundant  supply  of  pure  soft  water  for  London  ; 
and  the  Lake  of  Neuchatel  has  been  recently  proposed 
to  be  drawn  upon  for  supplying  Paris  with  water. 


MANCHESTER  WATERWORKS. 

Manchester  is  furnished  with  a  supply  of  excel- 
lent water,  collected  from  a  tract  of  high  land,  of 
19,300  acres,  lying  between  Manchester  and  Sheffield, 
drained  by  the  river  Etherow  and  its  tributaries,  the 
water  being  stored  in  a  series  of  reservoirs  formed  in 
the  Longdendale  Valley,  by  a  series  of  dams  across 
the  valley  impounding  the  flow  of  the  river  Etherow. 
The  works  were  commenced  in  1848,  and  completed  in 
1877.  Altogether  seven  collecting  reservoirs  have  been 
constructed,  in  an  almost  continuous  chain,  along  the 
Longdendale  Valley,  the  highest  two  of  which  have 
areas  of  135,  and  160  acres  respectively,  and  the 
others  have  areas  varying  from  63  to  13  acres.  Five 
of  these  reservoirs  communicate  with  service  reservoirs 
lower  down,  by  means  of  conduits  and  a  tunnel, 
if  miles  long,  with  a  fall  of  5  feet  in  a  mile,  and 
a  diameter  of  6  feet,  and  capable  of  passing  50  million 
gallons  of  water  in  a  day.  Before  reaching  the  first 
service  reservoir,  the  conduit  from  the  impounding  re- 
servoirs has  to  traverse  a  valley,  which  is  accomplished 

s 


274  Conduits,  and  Reservoir  Dams. 

by  means  of  cast-iron  inverted  syphon  pipes,  a  method 
always  adopted  now  for  crossing  valleys,  in  place  of  the 
aqueducts  by  which  the  Romans,  in  ancient  times,  main- 
tained their  channels  for  water  supply  at  a  uniform  slope 
in  passing  over  low-lying  lands.  The  tunnel  had  to  be 
carried  through  the  ridge  separating  the  valleys  of  the 
Etherow  and  the  Tame  ;  it  was  driven  by  the  aid  of 
five  shafts,  a  considerable  quantity  of  water  being  en- 
countered in  its  execution ;  and  the  work  was  completed 
in  1850,  The  Denton  reservoirs,  near  Manchester,  are 
lined  with  brickwork ;  and  the  water  is  there  passed 
through  copper  wire  gauze  to  intercept  any  floating 
matter.  The  water  is  then  distributed  by  gravity  from 
the  service  reservoirs  to  Manchester,  having  descended 
from  the  high  ground  by  gravity  alone. 

The  reservoirs  in  the  Longdendale  Valley  were 
formed  by  erecting  dams  of  earthwork,  70  to  100  feet 
high,  deposited  in  thin  layers,  and  formed  with  very  flat 
slopes,  protected  on  the  upper  side,  facing  the  water, 
with  a  layer  of  stones,  and  having  a  clay  puddle 
trench1  in  the  centre,  carried  up  from  a  solid  watertight 
stratum,  below  the  rest  of  the  embankment,  to  the  top. 
The  dam  for  forming  the  Woodhead  Reservoir,  the 
highest  up  the  valley,  was  commenced  in  1848  ;  but  it 
was  injured  by  a  flood  overtopping  it  in  1849,  when 
in  progress ;  and  eventually,  owing  to  the  defective 
nature  of  the  strata  upon  which  it  was  founded, 
resulting  in  continued  leakage,  a  new  dam  was  formed 
a  little  lower  down,  where  the  continuity  of  the 
rock  had  been  ascertained  by  boring;  and  the  lower 

1  When  clay  is  worked  or  kneaded  up  with  water,  it  becomes  more  im- 
pervious to  water  than  in  its  ordinary  condition,  and  is  termed  '  clay  puddle,' 
or  puddled  clay ;  and  this  material  is  used  to  form  the  central  watertight 
core,  wall,  or  trench  as  it  is  technically  called,  of  an  earthen  reservoir  dam. 


Waste  Weirs,  and  Compensation  Water.    275 

part  of  the  central  trench,  carried  down  to  a  depth  of 
about  90  feet  below  the  main  portion  of  the  em- 
bankment, was  filled  with  concrete  instead  of  clay 
puddle.  Accordingly,  the  Woodhead  Reservoir,  though 
one  of  the  first  works  commenced,  was  also  one  of 
the  last  of  the  works  finally  completed.  Discharge 
pipes  were  laid  at  first  under  the  embankments ;  but 
subsequently,  owing  to  dislocations  from  settlement  of 
the  superincumbent  mass,  the  pipes  were  carried  round 
the  side,  and  in  one  case  in  a  syphon  over  the  embank- 
ment, the  flow  through  them  being  controlled  by  valves. 
The  water  can  thus  be  discharged  into  the  next  lower 
reservoir,  or  into  a  side  conduit  leading  it  towards 
Manchester.  Waste  weirs  have  been  also  provided, 
over  which  the  surplus  water  flows  in  flood  time,  and 
is  discharged  along  a  flood  watercourse  into  the  river 
Etherow  below  the  lowest  reservoir.  Weirs  across  the 
main  streams,  above  the  reservoirs,  arrest  the  heavier 
sedimentary  matter  brought  down  in  flood  time,  and 
thus  keep  it  out  of  the  reservoirs.  The  two  impounding 
reservoirs  at  the  lower  end  of  the  valley  are  at  too  low 
a  level  to  supply  Manchester  through  the  conduit ;  and 
they  are  used  for  supplying  compensation  water  to  the 
river  Etherow,  so  that,  in  spite  of  the  large  volume  of 
its  flow  impounded  for  the  requirements  of  Manchester, 
its  discharge  may  never  be  less  than  a  definite  volume 
in  the  twenty-four  hours,  a  condition  imposed  upon  the 
promoters  of  such  schemes  of  water  supply  to  guard 
the  interests  of  riparian  proprietors  lower  down. 

The  mountain  streams  to  the  north  of  the  reservoirs 
are  intercepted  by  the  supply  conduit  before  reach- 
ing the  reservoirs ;  and  in  ordinary  weather  the  whole 
of  their  flow  is  conveyed  direct  to  Manchester.  These 


276   Capacity  and  Cost  of  Manchester  Waterworks. 

streams,  however,  are  made  to  flow  over  special  separ- 
ating weirs,  so  that,  when  their  flow  is  moderate,  the 
water  drops  quietly  over  the  weir,  and  through  an  open- 
ing at  its  foot,  into  the  conduit.  When  they  become 
turbid  in  flood  time,  and  unsuitable  for  water  supply, 
their  volume  and  velocity  being  increased,  they  leap 
over  the  opening,  and  pass  into  subsiding  reservoirs, 
whence  the  water  can  be  passed  away  for  compensation 
water,  or  into  the  main  reservoirs  after  becoming  clear. 
The  total  storage  capacity  of  the  whole  of  the  reser- 
voirs is  about  4590  million  gallons  ;  and  the  total  avail- 
able supply  for  the  district  is  about  24  million  gallons 
a  day.  Considering  that  the  consumption  of  water 
in  Manchester,  for  all  purposes,  rose  from  8  million 
gallons  per  day  in  1855  to  18  million  gallons  per  day 
in  1 88 1,  it  is  evident  that  the  scheme  of  1848,  ample 
as  it  originally  appeared  to  be,  is  becoming  insuffi- 
cient for  the  increasing  requirements  of  Manchester. 
In  1879,  accordingly,  authority  was  obtained  for  pro- 
curing an  additional  supply  from  Thirlmere,  the  works 
for  which  are  in  progress.  The  total  cost  of  the  ex- 
isting Manchester  Waterworks  has  amounted  to  about 
£3,070,000. 

Thirlmere  Water  Supply. — In  seeking  for  an  addi- 
tional water  supply  for  Manchester,  it  was  decided  to 
go  to  the  lake  district  to  the  north  ;  and  from  the  three 
lakes  at  a  sufficient  elevation  to  supply  Manchester 
with  water  by  gravitation,  namely,  Haweswater,  Ulles- 
water,  and  Thirlmere,  the  latter  was  finally  selected  as 
the  most  suitable.  Though  Thirlmere  is  considerably 
smaller  than  Ulleswater,  its  level  can  be  raised  with- 
out injury  to  property ;  it  is  at  a  higher  level  than 


.    Supply  of  Water  from  Thirlmere.          277 

Ulleswater ;  it  necessitates  a  considerably  less  length  of 
tunnel,  at  a  much  less  depth  below  the  surface,  for  lead- 
ing the  water  from  it ;  and  it  is  situated  in  the  middle  of 
the  most  rainy  district  in  England.  The  scheme  now  in 
progress  provides  for  raising  the  level  of  the  lake  50  feet, 
by  a  dam  across  its  natural  outlet  at  the  end  furthest  off 
from  Manchester,  in  order  to  increase  the  storage  capacity 
of  the  lake,  which  has  an  area  of  only  350  acres,  so  that 
the  water  level  may  not  be  unduly  lowered  in  dry  seasons. 
The  eventual  maximum  daily  supply  of  50  million  gallons 
will  be  conveyed  to  Manchester  by  an  aqueduct,  or  con- 
duit, about  100  miles  long,  starting  from  the  upper  end 
of  the  lake,  in  a  tunnel  3  miles  long  under  Dunmail  Raise. 
The  aqueduct  will  be  formed  partly  in  tunnel,  and  will  be 
chiefly  constructed  in  open  cutting  in  the  solid  rock,  sub- 
sequently covered  over  by  an  arch  ;  and  it  will  pass  to  the 
east  of  Windermere,  Kendal,  Lancaster,  and  Preston,  and 
by  Chorley  to  near  Bolton,  whence  the  water  will  be  con- 
veyed in  iron  pipes  to  the  service  reservoirs  near  Man- 
chester. Inverted  iron  syphon  pipes  will  carry  the  supply 
across  the  valleys  of  the  Kent,  the  Lune,  the  Ribble,  and 
other  rivers.  The  water  will  descend  from  the  lake  wholly 
by  gravitation,  as  the  lake  is  533  feet  above  mean  sea 
level.  The  principal  works  are  being  carried  out  to  their 
full  extent,  the  aqueduct  as  far  as  Bolton  being  made 
large  enough  to  pass  the  whole  future  supply,  though  at 
first  provision  will  only  be  made  near  Manchester  for 
furnishing  a  supply  of  10  million  gallons  a  day.  The 
necessary  additions  will  be  made  in  the  future,  at  the 
Manchester  end,  to  admit  the  further  supply  in  in- 
crements of  10  million  gallons,  as  required  for  the 
wants  of  the  city.  The  estimate  for  the  first  portion 
of  the  supply,  involving  the  construction  of  the  aque- 


278      Supply  and  Cost  of  Thirtmere  Scheme. 

duct  and  dam,  is  £1,740,000 ;  and  the  total  ultimate 
cost  of  the  works,  for  the  whole  supply  of  50  million 
gallons  a  day,  is  estimated  at  £3,500,000.  These 
works  will,  accordingly,  eventually  furnish  more  than 
double  the  existing  water  supply  of  Manchester;  and 
therefore  the  total  supply  of  water  provided  for  will 
be  three  times  the  present  supply.  The  cost,  also, 
of  the  new  supply  appears  very  moderate,  in  spite 
of  the  great  distance  it  has  to  be  conveyed,  when 
compared  with  the  expenditure  involved  in  furnishing 
the  present  supply  of  about  half  the  volume  from  a 
much  nearer  district  Moreover,  though  the  initial  cost 
of  procuring  the  first  instalment  of  10  million  gallons 
a  day,  only  a  fifth  of  the  whole,  is  comparatively 
large,  it  is  a  great  advantage  for  Manchester  to  have 
secured  a  gathering  ground  which  might  later  on  have 
been  appropriated  by  others,  and  which  will  amply 
supply  the  city  for  a  long  period. 

VYRNWY   DAM   AND   LAKE. 

Liverpool  has  for  many  years  been  supplied  with 
water  from  wrells  in  the  red  sandstone,  and  from 
reservoirs  in  the  Rivington  district,  near  the  headwaters 
of  the  river  Yarrow.  Though  Liverpool  is  not  a 
manufacturing  town  like  Manchester,  it  has  a  much 
larger  population ;  and  the  existing  supply  of  water  has 
become  inadequate  for  its  requirements.  Liverpool, 
accordingly,  has  been  obliged  to  search  at  a  distance 
for  a  gathering  ground  for  an  additional  supply  ;  and 
the  site  selected  is  the  upper  valley  of  the  Vyrnwy 
River,  a  tributary  of  the  Severn  near  its  source.  The 
Vyrnwy  River,  rising  in  a  mountainous  part  of  Mont- 


Vyrnwy  Reservoir  Dam  and  Lake.        279 

gomeryshire,  has  been  arrested  by  a  masonry  dam 
stretching  across  a  gorge  of  the  valley ;  and  the  water 
thus  impounded,  rising  to  the  level  of  the  top  of  the 
dam,  has  flooded  the  lower  portions  of  the  valley 
above  the  dam,  thus  forming  an  artificial  lake,  1121 
acres  in  extent.  (See  illustration.}  This  portion  of  the 
valley  had  a  little  village,  with  its  church,  situated 
below  the  level  of  the  proposed  reservoir ;  and  therefore 
a  new  church  had  to  be  built,  on  a  suitable  neighbour- 
ing site,  before  the  valley  could  be  submerged. 

The  foundations  for  the  masonry  dam  had  to  be 
carried  down  to  a  considerable  depth  below  the 
surface,  through  porous  material,  to  reach  the  solid 
rock  ;  so  that,  in  the  deepest  place,  the  bottom  of  the 
dam  is  132  feet  below  the  level  of  the  lake,  though 
the  deepest  part  of  the  lake  is  only  84  feet.  The  dam 
rests  upon  the  rock  throughout,  a  condition  necessary 
for  masonry  dams,  to  secure  them  against  settlement, 
or  against  the  percolation  of  water  under  their  founda- 
tions leading  to  settlement,  and  consequent  dislocation, 
and  on  account  of  the  weight  on  the  foundations,  due 
to  the  weight  of  the  masonry  combined  with  the 
water  pressure  on  the  dam  when  the  reservoir  is 
full.  The  dam  has  been  built  of  solid  masonry 
throughout,  from  the  foundations  to  the  water  level  of 
the  lake,  with  the  exception  of  two  tunnels,  15  feet 
in  diameter,  just  above  the  surface  of  the  ground 
towards  each  end  of  the  dam,  which  served  to  dis- 
charge the  flow  of  the  river  during  the  construction 
of  the  dam,  but  which  are  now  closed  with  only  dis- 
charge pipes  encased  in  them.  The  dam  has  a  nearly 
vertical  face  on  its  upper  side,  facing  the  lake  ;  but  it 
has  a  curved  face  on  its  lower  side,  so  that  it  increases 


280  Dimensions  of  Dam,  and  Discharge  Pipes. 

in  width  from  about  22  feet  near  the  top  to  120  feet 
at  the  deepest  part  of  the  base,  a  form  necessitated  by 
the  increase  of  the  water  pressure  against  the  dam 
with  the  depth ;  and  it  contains  between  six  and  seven 
hundred  thousand  tons  of  masonry.  A  road  is  carried  on 
arches  over  the  top  of  the  dam  ;  and  the  surplus  water 
flows  over  the  dam  under  the  arches,  so  that  these  open- 
ings serve  as  a  waste  weir  to  discharge  the  excess  of  water 
into  the  stream  below.  The  length  of  the  dam  along  the 
top  is  1172  feet;  its  height  from  the  lowest  part  of  the 
foundations  to  the  parapet  of  the  roadway  is  161  feet ; 
and  the  width  of  the  roadway  along  the  top  is  about 
20  feet.  The  pipes  placed  in  the  old  discharge  tunnels 
are  reached  from  the  top,  through  a  valve  chamber  and 
a  valve  pit  above  each  tunuel.  The  pipe  in  the  north- 
eastern tunnel,  3^  feet  in  diameter,  and  controlled  by 
two  valves  from  the  valve  chamber  below  the  roadway, 
is  intended  to  regulate  the  water  level  of  the  lake. 
The  two  pipes  placed  in  the  south-western  tunnel 
are  similarly  controlled  ;  and  one  of  them,  18  inches  in 
diameter,  provides  for  the  discharge  of  the  daily  com- 
pensation water  to  the  stream  below  of  not  less  than 
10  million  gallons ;  whilst  the  other,  30  inches  in 
diameter,  discharges  the  monthly  compensation  water 
of  four  times  the  above  volume,  for  the  Severn  Com- 
missioners, on  thirty-two  days  between  March  and 
October.  The  works  were  authorised  in  1880;  and  in 
November  1888,  the  dam  was  sufficiently  near  comple- 
tion to  enable  the  valves  in  the  dam  to  be  closed ;  and 
the  filling  of  the  reservoir  was  accomplished  in  the 
course  of  1889. 

The  Vyrnwy   Lake,   formed   by   means   of  the   dam, 
has   an    area   of   1121    acres,   a   length   of  4f   miles,    a 


Vyrnwy  Lake  and  Straining  Tower.       281 

width  of  from  J  to  f  of  a  mile,  and  a  maximum 
depth  of  84  feet.  The  storage  capacity  of  the  lake, 
down  to  the  level  to  which  water  may  be  drawn  off 
for  Liverpool  at  the  rate  of  40  million  gallons  per  day, 
amounts  to  12,130  million  gallons.  The  lake,  with  its 
surroundings,  is  very  picturesque ;  and,  out  of  sight 
of  the  dam,  it  is  difficult  to  realise  that  it  is  artificial, 
except  where  an  old  road  abruptly  terminates  at  the 
lake,  and  at  a  few  points  where  trees  and  hedges  are 
only  partially  submerged.  A  road  constructed  round 
the  lake  enables  it  to  be  viewed  from  every  point ; 
and  the  wildest  part  of  the  district  is  at  the  head  of 
the  lake  which  has  added  a  fresh  beauty  to  the  valley ; 
whilst  the  dam,  being  formed  of  dark  stone,  presents 
no  unsightly  appearance  of  newness,  and  offers  a 
striking  contrast  to  the  cascade  falling  over  it  when 
the  lake  overflows.  (See  illustration.) 

The  Vyrnwy  tower,  a  picturesque  structure  with  a 
conical  roof,  has  been  built  down  the  slope  of  the  valley ; 
so  that  it  now  stands  in  deep  water  near  the  side  of  the 
lake,  and  is  reached  from  the  road  by  a  stone  bridge. 
Adjoining  this  tower  are  the  cylindrical  inlet  valves, 
by  which  the  water  can  be  drawn  off  from  various 
levels,  according  to  the  level  of  the  lake  ;  so  that  the 
purest  and  most  bleached  surface  water  may  be 
delivered  into  the  tower,  by  lifting  one  or  more 
lengths  of  iron  pipes  placed  vertically  over  the 
circular  inlet.  The  water  thus  delivered  into  the 
tower  will  pass  through  cylinders  of  very  fine 
copper  wire  gauze  (which  will  arrest  all  but  the 
finest  particles  in  suspension  in  the  water),  before 
reaching  the  conduit  which  will  convey  it  to  Liver- 
pool. A  concrete  culvert  in  the  bed  of  the  lake 


282      Tunnels,  etc.,  from  Vyrnwy  to  Liverpool. 

leads  from  the  Vyrnwy  tower  to  the  Hirnant  Tunnel, 
2j  miles  long,  which  will  convey  the  supply  from  the 
lake,  through  a  ridge,  into  another  valley,  the  nearest 
point  of  the  conduit  being  over  3  furlongs  distant 
from  the  dam.  The  length  of  the  aqueduct  between 
Lake  Vyrnwy  and  the  Prescot  service  reservoirs,  near 
Liverpool,  is  over  68  miles ;  and  in  this  distance  it 
has  to  pierce  through  three  ridges  in  tunnel,  to  cross 
several  streams  and  canals ;  and  it  has  to  pass,  in 
steel  tubes,  both  under  the  river  Weaver,  and  through 
a  subway  under  the  Manchester  Ship  Canal,  and  also 
in  steel  tubes  through  a  tunnel  under  the  river  Mersey 
above  Runcorn,  carried  out,  like  the  Thames  subways, 
with  a  series  of  segmental  cast-iron  rings.  (See page  106.) 
The  main  portion  of  the  aqueduct  will  consist  of  three 
lines  of  cast-iron  pipes,  laid  not  less  than  3  feet  below 
the  surface,  and  following  the  general  contour  of  the 
country  which  it  traverses.  One  line  of  pipes  only, 
42^  inches  in  diameter,  has  hitherto  been  laid,  which 
will  be  capable  of  discharging  over  13  million 
gallons  a  day,  or  a  third  of  the  available  supply  of 
40  million  gallons  a  day  that  can  be  drawn  from 
the  lake  by  laying  the  other  two  lines  of  pipes 
as  the  requirements  of  Liverpool  increase.  The  lake, 
at  its  lowest  available  water  level,  is  496  feet  higher 
than  the  top  water  level  of  the  Prescot  reservoirs ; 
so  that  the  average  fall  from  the  Vyrnwy  lake  to 
Prescot  is  nearly  7^  feet  per  mile.  The  dis- 
charge will  accordingly  be  readily  effected  by 
gravitation,  though  the  fall  has  not  been  made 
uniform  throughout,  in  order  to  reduce  the  length 
of  tunnelling,  and  the  pressure  at  certain  places  on 
the  pipes  passing  across  valleys.  With  the  object  of 


Balancing  Reservoirs,  and  Water  Tower.      283 

diminishing  the  head,1  and  consequently  the  pressure 
of  water  on  the  pipes,  which,  with  a  closed  conduit 
throughout,  would  have  reached  496  feet  vertical  water 
pressure  at  Prescot  when  the  flow  was  stopped  there, 
and  848  feet  in  the  tunnel  under  the  Mersey,  the  aque- 
duct has  been  divided  into  six  sections,  between  each 
of  which  a  reservoir  has  been  formed,  in  which  the 
water  can  rise  and  overflow;  so  that  the  water  pressure 
is  reduced  to  the  difference  of  the  level  between  the 
highest  and  the  lowest  points  of  each  section.  In 
four  out  of  the  five  reservoirs  constructed  for  this 
purpose,  advantage  has  been  taken  of  places  where 
the  ground  level  rises  to  the  line  of  the  hydraulic 
gradient,  or  the  average  fall,  or  gradient,  from  the 
lake  to  the  Prescot  reservoirs.  The  fifth  reservoir  has 
had  to  be  constructed  on  the  top  of  a  tower,  113 
feet  high  and  90  feet  in  diameter,  built  on  the 
summit  of  Norton  Hill,  as  none  of  the  ground  in 
the  vicinity  along  the  line  traversed  attained  the 
height  of  the  hydraulic  gradient.2  The  basin-shaped 
reservoir,  placed  on  the  top  of  this  tower,  formed 
of  steel  plates,  will  contain  651,000  gallons  of  water. 

3  A  head  of  water  is  the  difference  of  the  water  level  at  the  two  extremi- 
ties of  a  closed  conduit,  or  on  the  two  sides  of  a  reservoir  dam,  or  any  barrier 
such  as  a  weir  in  a  river.  The  water  pressure  increases  in  proportion  to  the 
head,  being  equal,  for  any  given  area,  to  the  weight  of  a  volume  of  water 
having  the  cubical  contents  of  this  area  multiplied  by  the  head. 

2  A  conduit,  or  aqueduct,  through  which  the  water  from  a  reservoir  is 
conveyed  by  gravity,  follows  the  undulations  of  the  surface  where  the  sur- 
face is  not  higher  than  the  hydraulic  gradient,  or  line  of  average  fall  between 
the  two  extremities.  Though,  however,  the  conduit  may  be  laid  below  the 
level  of  this  mean  gradient,  which  merely  causes  a  water  pressure  in  the 
conduit  proportionate  to  the  vertical  distance  of  the  conduit  at  any  point 
below  the  mean  gradient  line,  the  conduit  must  never  be  raised  above  this 
line,  otherwise  the  water  would  cease  to  flow  at  this  part ;  and  in  such 
cases  tunnelling  or  deep  cutting  has  to  be  resorted  to,  in  order  to  place  the 
conduit  at  the  level  of  the  hydraulic  gradient. 


284    Unsatisfactory  State  of  London  Water  Supply. 

The  reservoir  near  Oswestry,  situated  at  the  outlet  of 
the  Llanforda  tunnel,  leads  to  -filter  beds  a  little  lower 
down,  where  the  water  will  be  purified  from  any  fine 
matters  in  suspension  which  may  have  passed  the 
strainers  in  the  tower  on  the  lake. 

The  total  estimated  cost  of  these  works,  for  pro- 
viding the  first  instalment  of  about  13^  million 
gallons  of  water  a  day  for  Liverpool,  is  .£1,991,200, 
or  in  round  numbers  about  £2,000,000.  Two  other 
instalments,  however,  can  be  provided  when  required, 
bringing  up  the  total  supply  to  40  million  gallons  a 
day,  at  the  cost  of  laying  two  more  lines  of  pipes ; 
for  the  dam,  lake,  tunnels,  and  some  other  portions 
of  the  work,  have  had  to  be  constructed  to  the  full 
extent  needed  for  the  whole  of  the  proposed  supply. 
Liverpool,  accordingly,  like  Manchester,  is  providing 
itself  with  a  water  supply  of  excellent  quality,  which 
is  capable  of  gradual  extension,  and  will  suffice  for 
the  requirements  of  the  city  for  a  long  period. 

London  possesses  the  natural  advantage  over  Liver- 
pool and  Manchester  of  the  river  Thames,  from  which 
it  has  continually  to  draw  larger  supplies  of  water. 
The  water,  however,  supplied  from  the  Thames  and 
other  sources  is  distinctly  inferior  in  quality  to  the 
water  which  the  Liverpool  and  Manchester  corpora- 
tions have  provided,  at  considerable  expense,  but  with 
great  care  and  foresight,  for  their  respective  cities. 
In  London  the  supply  is  furnished  by  several  inde- 
pendent water  companies,  at  a  considerable  profit  to 
themselves ;  but  the  service  is  not,  for  the  most  part, 
constant  as  at  Liverpool  and  Manchester,  being  only 
delivered  into  cisterns  once  or  twice  in  the  day,  in- 
stead of  being  drawn  straight  and  fresh  from  the 


Control  and  Extension  of  London  Water  Siipply.   285 

mains.  London  and  its  suburbs  are  increasing  at  a 
very  rapid  rate ;  and  already  the  whole  of  the  dry 
weather  flow  of  the  river  Lee,  and  more  than  one- 
third  of  the  summer  discharge  of  the  river  Thames 
at  Teddington,  are  abstracted  for  water  supply,  As 
the  metropolitan  water  supply  has  been  quadrupled 
within  the  last  forty  years,  and  the  average  yearly 
increase  has  exceeded  31  million  gallons  a  day,  it  is 
evident  that  the  Thames  will  have  to  be  still  more 
largely  drawn  upon  year  by  year,  and  eventually  its 
whole  summer  flow  abstracted,  or  fresh  sources  of 
supply  sought  for.  It  is  therefore  clearly  expedient, 
under  existing  circumstances,  that  the  whole  water 
supply  of  the  metropolis  should  be  brought  under 
the  control  of  a  single  public  body,  for  the  general 
welfare  of  its  inhabitants,  and  that  no  less  care  and 
forethought  should  be  used  to  secure  a  pure  and 
ample  supply  in  the  future  for  the  vast  and  rapidly 
increasing  population  of  London  than  has  been  exer- 
cised by  the  local  authorities  for  the  smaller  com- 
munities of  Liverpool  and  Manchester. 


CHAPTER  XVI. 

THE    EDDYSTONE    LIGHTHOUSE;     AND    THE 
EIFFEL    TOWER. 

LIGHTHOUSES  are  of  the  utmost  service  to  navigation, 
in  both  indicating  to  vessels  their  proximity  to  land, 
and  the  particular  locality  by  a  special  arrangement  of 
flashes  of  light,  and  in  warning  them  from  running 
on  to  rocks  at  some  distance  from  the  land.  The 
most  powerful  lights  are  exhibited  from  lighthouses  on 
the  coast,  as,  for  instance,  on  important  headlands 
like  St  Catherine's,  the  southernmost  point  of  the  Isle 
of  Wight,  where  the  lighthouse  emits  the  strongest 
ray  of  electric  light  in  the  world  ;  but  the  lighthouses 
possessing  the  greatest  interest  are  those  which,  erected 
on  rocks  barely  emerging  from  the  waves  far  out  at 
sea,  stand  as  solitary  outposts  to  warn  passing  vessels 
to  keep  clear  of  the  reef  which  they  mark.  Not  only 
does  their  desolate  position,  far  off  from  any  sheltering 
land,  on  a  rocky  bed  almost  continually  lashed  with 
surf,  form  a  remarkable  contrast  to  their  beneficent 
object,  but  their  very  situation  renders  it  marvellous 
that  any  structure  can  be  made  to  stand  on  such  an 
exposed  site,  subjected  to  the  constant  attacks  of  the 
waves.  It  is,  in  fact,  a  work  of  great  difficulty  and 
danger,  requiring  the  utmost  skill  and  perseverance,  to 


Difficulties  in  Building  Rock  Lighthouses.   287 

found  a  lighthouse  on  a  very  limited  ledge  of  rock, 
frequently  submerged,  and  only  approachable  in  the 
calmest  weather  and  at  low-water.  The  only  advan- 
tages possessed  by  these  lighthouses  are  that  the  rocks 
on  which  they  are  built  are  of  the  hardest  and  firmest 
character,  having  for  ages  withstood  the  perpetual 
action  of  the  sea ;  and  that  the  structures  themselves, 
unlike  breakwaters,  offer  little  surface  to  the  waves. 
In  spite,  however,  of  the  difficulties  attending  their 
erection,  many  lighthouses  have  been  established  on 
outlying  rocks  round  the  British  and  foreign  coasts, 
of  which  the  Bell  Rock,  Bishop  Rock,  Wolf  Rock, 
Skerry vo re,  Ar-men,  and  Minot's  Ledge  are  notable 
instances.  The  most  remarkable,  however,  of  these 
lighthouses,  on  account  of  the  important  and  exposed 
nature  of  its  position,  the  interest  of  its  history,  and 
the  size  of  the  structure,  is  the  celebrated  Eddystone 
Lighthouse,  the  rebuilding  of  which,  on  a  grander  scale, 
has  been  accomplished  within  the  last  thirteen  years. 


EDDYSTONE  LIGHTHOUSE. 

The  Eddystone  rocks,  upon  which  four  lighthouses 
have  been  successively  built,  are  a  group  of  gneiss  rocks 
situated  in  the  English  Channel,  about  9  miles  from 
the  nearest  coast  of  Cornwall,  and  14  miles  from  the 
Plymouth  breakwater,  which  are  mostly  below  high- 
water.  As  these  rocks  stand  out  from  the  coast,  nearly 
in  the  track  of  vessels  going  up  or  down  the  Channel, 
they  were  the  scene  of  frequent  wrecks  before  their 
position  was  marked  by  the  erection  of  a  lighthouse. 
The  first  lighthouse  erected  on  these  rocks,  nearly  two 


288          Successive  Eddy  stone  Lighthouses* 

hundred  years  ago,  was  constructed  of  wood  resting 
upon  a  stone  base,  having  a  total  height  of  100  feet. 
It  was  commenced  in  1696,  and  completed  in  1700,  the 
light  having  been  first  exhibited  at  the  end  of  1698, 
and  the  structure  subsequently  strengthened.  This  light- 
house was  polygonal,  with  numerous  projections,  and 
somewhat  resembling  a  Chinese  pagoda,  having  an  open 
gallery  about  half  way  up,  through  which  the  waves 
were  liable  to  dash  in  a  storm,  as  the  site  is  open  to  the 
Atlantic.  Altogether,  the  building  was  very  unsuited 
for  its  purpose,  in  such  an  exposed  situation ;  and  in 
November  1703,  when  the  builder,  Mr  Winstanley,  was 
superintending  some  repairs  in  it,  a  violent  storm  swept 
the  lighthouse  away.  The  second  lighthouse  was  also 
built  of  wood,  in  1706-9,  but  of  a  conical  form;  it  was 
connected  to  the  rock  by  iron  bolts,  and  its  weight 
was  increased  by  introducing  courses  of  stone  at 
intervals.  This  lighthouse  successfully  withstood  the 
storms  for  nearly  fifty  years,  but  was  destroyed  by 
fire  in  1755.  Smeaton  was  then  entrusted  with  the 
construction  of  a  new  lighthouse,  which  he  built  of 
stones  dovetailed  together,  in  1756-59,  conical  in  form, 
but  spreading  out  more  at  the  base.  This  lighthouse 
was  85  feet  high ;  and  being  a  model  of  solidity  and 
strength,  it  withstood  the  fury  of  the  waves  on  the  reef 
for  over  a  hundred  years,  though  the  water  at  times 
dashed  over  the  lantern.  Though,  however,  the  light- 
house remained  intact,  the  sea,  in  striking  the  lighthouse, 
began  to  undermine  the  rock  upon  which  it  stood  ;  so 
that  at  length  it  was  decided  to  take  it  down,  after 
erecting  another  lighthouse  in  its  place  on  an  adjacent 

rock. 

The  new  Eddystone  Lighthouse  was  commenced   in 


Foundations  of  New  Eddy  stone  Lighthouse.   289 

1878,  on  a  rock  120  feet  south-south-east  of  Smeaton's 
lighthouse.      The    great   difficulties    in    lighthouse    con- 
struction   on    isolated    rocks    are,   the   levelling    of    the 
rock  to  receive  the  foundation  courses  of  the  lighthouse 
tower  ;  the  boring  of  the  holes  for  fastening  the  masonry 
to    the  rock ;   and   the   laying  of  the   first   few  courses, 
owing  to  the  few  days  on  which  a  landing  can  be  effected, 
and  the  short  period  during  which  it  is  possible  to  work 
upon   a   rock,   little   raised    sometimes   above   low-water 
level,    and    exposed    to    the    wash    of    waves    except 
in    the   calmest   weather.      In    this   respect    the    site  of 
the     new    lighthouse    was     less     favourable     than     the 
original  site;    for  whereas   the   base   for   the   new  large 
tower     is    44    feet     in     diameter,     as     compared     with 
26  feet   in   the   old   tower,    and    therefore    the    area    of 
the  foundation    and  the  work    in   the  first   few   courses 
was  much  greater,  the  surface  of  the  rock  was  altogether 
lower,  and  a  large  portion  below  low-water  level  at  the 
new  site,  instead  of  being  entirely  above  low-water  and 
partly    above   high-water   as   in   the  original  site.     The 
work,   however,   of  preparing   the   rock  and  laying  the 
foundation  courses  at  this  low  level  was  greatly  facili- 
tated by  building  a  temporary  dam   of  brickwork,  laid 
in    quick-setting     cement,    round    the    site,    7    feet    in 
height,  out  of  which  enclosure  the  water  was  pumped 
by   steam   power   from   the   attendant   steamer  as  soon 
as    the    tide    fell    below   the   top    of    the    dam,   which 
enabled   the    men   on    calm    days    to    commence   work 
much  earlier,  to  work  at  the  portion   below  low-water 
level  which  was  thus  laid  dry,  and  to  continue  working 
till   the   tide   rose   again    to   the   top   of  the   dam.      A 
platform,  also,  was  erected  over  the  site,  10  feet  above 
low-water,   on   which    the    men    could    land    with   their 

T 


290      Erection  of  New  Eddy  stone  Lighthouse. 

tools,  so  as  to  be  in  readiness  to  start  work  the 
moment  the  enclosure  round  the  foundations  was  dry. 
The  stones,  moreover,  were  rapidly  landed  by  steam 
power,  from  the  steamer  in  attendance,  on  to  the  site  as 
required.  In  this  way  no  available  time  was  lost  after 
the  commencement  of  the  works  in  July  1878.  An 
iron  mast,  25  feet  long,  with  two  jibs  acting  as  cranes, 
was  erected  in  the  centre  of  the  foundations,  and  was 
at  first  sunk  5  feet  in  the  rock,  and  subsequently  lifted 
up  higher  as  the  work  proceeded.  One  of  the  jibs  was 
used  for  assisting  in  the  landing  of  stones  from  the 
steamer,  and  the  other  for  setting  the  stones  in  the  tower. 
By  June  1879  the  preparation  of  the  foundations  and 
the  preliminary  work  were  sufficiently  completed  to  en- 
able the  laying  of  the  stones  to  be  commenced.  All  the 
stones  are  dovetailed,  both  horizontally  and  vertically,  so 
that  they  are  firmly  fixed  to  the  adjacent  stones  in  the 
same  course,  and  also  to  the  courses  below  and  above. 
The  stones  of  the  foundation  courses  are  each  sunk  at 
least  I  foot  into  the  rock,  and  secured  to  the  rock  by 
two  Muntz  metal  bolts,  ij  inches  in  diameter.  The 
base  of  the  lighthouse  has  been  made  cylindrical  for  a 
height  of  22  feet ;  and  this  portion  was  completed  in 
July  1880,  two  years  after  the  commencement  of  the 
work,  518  hours  of  work  having  been  accomplished  in 
1879,  during  131  landings  on  the  site.  The  actual 
tower  commences  from  the  top  of  this  base,  with  a  some- 
what curved  slope  on  the  face,  so  that,  like  all  lighthouse 
towers,  it  is  reduced  in  diameter  as  it  ascends,  the  reduc- 
tion being  greatest  near  the  bottom.  (See  illustra- 
tion.} The  cylindrical  base  was  adopted  in  order  to 
prevent  the  waves  running  up  the  tower  as  they  did 
up  the  old  lighthouse,  rising  sometimes  above  the  top, 


Internal  A  rrangements  of  L ighthouse.     291 

descending  with  some  force  on  the  lantern,  and  hiding 
the  light  for  about  half  a  minute.  The  cylindrical  base, 
rising  2\  feet  above  high-water  spring  tides,  diverts  the 
waves,  and  also  forms  a  convenient  landing  place.  The 
tower  was  built  of  solid  granite  up  to  23  feet  above  the 
base,  with  the  exception  of  the  central  cylindrical  hollow 
left  for  the  water  tank.  Above  this  the  entrance  to 
the  lighthouse  was  constructed,  which  is  reached  by 
a  gun-metal  ladder  from  the  base  of  the  tower;  and 
two  similar  ladders  give  access  on  two  sides  up  the 
cylindrical  base.  The  tower  contains  nine  rooms, 
including  the  entrance  room  at  the  bottom,  just  above 
the  solid  portion,  and  the  service  room  at  the  top 
below  the  lantern  ;  the  intermediate  rooms  consisting 
of  two  oil  rooms,  a  store  room,  a  crane  room  from 
which  a  crane  hoists  stores,  the  living  room,  the  low 
light  room  from  which  a  white  fixed  light  is  exhibited 
to  mark  a  shoal  3^-  miles  distant,  and  the  bedroom 
just  below  the  service  room.  The  seven  upper  rooms 
are  14  feet  in  diameter,  and  10  feet  high ;  and  a  wind- 
ing staircase  inside  leads  from  the  entrance  room  to 
the  lantern,  giving  access  to  each  room.  The  tower 
was  raised  nearly  to  the  top  of  the  first  oil  room  in 
November  1880,  completing  the  season's  work,  which 
had  been  commenced  in  March,  657  hours  of  work  having 
been  accomplished  during  no  landings  in  that  period. 
As  the  tower  had  been  raised  above  the  reach  of  the 
waves,  work  could  be  commenced  again  as  soon  as 
a  landing  could  be  effected,  about  the  middle  of 
January  1881  ;  the  last  stone  was  laid  in  June  1881  ; 
and  the  lantern  was  erected  before  the  end  of  the 
year.  A  temporary  light  was  exhibited  from  the  new 
lighthouse  in  February  1882,  and  the  light  in  the  old 


29 2      Old  and  New  Methods  of  Illumination. 

tower  was  discontinued ;  and  in  May  1882  the  per- 
manent lamps  were  lit  in  the  new  lighthouse,  within  four 
years  of  the  commencement  of  the  work.  The  lantern 
and  four  rooms  of  the  old  tower  were  taken  down, 
and  the  staircase  well  and  entrance  below  this  level 
were  filled  up  with  masonry ;  so  that  the  base  of  the 
old  tower  forms  a  distinguishing  mark  by  day  along- 
side the  new  lighthouse.  (See  illustration^]  The  portion 
taken  down  has  been  erected  on  a  new  granite  base 
on  Plymouth  Hoe,  to  form  a  landmark  out  at  sea, 
and  to  serve  as  a  memorial  of  Smeaton's  light- 
house. 

The  light  originally  exhibited  from  Smeaton's  light- 
house consisted  of  twenty-four  tallow  candles,  which, 
unassisted  by  any  lenses,  emitted  a  light  which  has 
been  estimated  as  equivalent  to  an  illuminating  power 
of  67  standard  candles,  such  as  are  used  at  the  present 
day  for  measuring  the  intensity  of  gas  flames.  Latterly 
the  fixed  colza  oil  light  exhibited  from  this  lighthouse, 
aided  by  lenses,  had  an  intensity  equal  to  one  hundred 
times  the  original  light.  The  new  lighthouse  is  provided 
with  two  superposed  seven-wick  burners,  placed  in  the 
foci  of  two  superposed  tiers  of  lenses ;  and  each  burner 
emits  a  light  having  an  intensity  of  950  candles,  which  is 
raised  by  the  lenses,  in  the  direction  of  the  ray  of  illumina- 
tion, to  79,800  candles.  On  clear  nights,  when  the  light 
of  the  lighthouse  on  Plymouth  breakwater,  10  miles  off", 
is  distinctly  seen,  the  lower  burner  alone  is  lighted  at 
its  lowest  power  of  450  candles ;  but  whenever  any 
mist  obscures  the  light  on  the  breakwater,  the  full 
power  of  1900  candles  is  exhibited,  with  an  intensity 
through  the  lenses  of  159,600  candles.  This  maximum 
intensity  is  more  than  twenty-three  times  the  power 


Distinguishing  Flashing  Lights  at  Eddy  stone.    293 

of  the   light   previously   exhibited    from   the   old    light- 
house,  and    nearly   two    thousand    four    hundred    times 
the   power   of  the   original    light,  and   is   the   strongest 
light  hitherto  produced  by   oil  in  a  lighthouse.     Colza 
oil   is   always  used  in  isolated  lighthouses,  on   account 
of    its    greater   safety    against    fire ;    whereas    in    light- 
houses   on    the    coast,    mineral    oil     is    employed,     as 
cheaper  and   equally  efficient     In   order   to  distinguish 
the    Eddystone    light    from    other    lights,   the    light    is 
made    to    exhibit    a  double   flash   at   intervals   of   half 
a  minute,  by  causing  the  optical   apparatus  to  revolve 
and   obscure   the   light   at   intervals.      Each   flash   lasts 
three  and  a  half  seconds,  with  an  interval  of  darkness 
of  three  seconds  between  the  first  and  the  second  flash, 
which    latter    is    followed    by    an    eclipse    of    the    light 
for  twenty  seconds.     By  modifying  these  arrangements 
of    flashes   in   every   case,   each    lighthouse    exhibits    a 
distinctive    feature   in   its   light ;    so    that    the    mariner 
not    only   sees   the   light,    but    also    is    informed    from 
what  lighthouse   it   proceeds,  and   therefore  by  sighting 
a    light    knows    also    what    position    he    has    reached. 
Many    wrecks    have    occurred    from    sailors    mistaking 
one   light   for   another,    an    error    which   these   flashing 
arrangements  are  intended  to  obviate. 

Two  bells  suspended  on  each  side  of  the  light- 
house, under  the  gallery  round  outside  the  lantern, 
serve  to  give  warning  in  foggy  weather,  the  clappers 
being  moved  by  the  same  machinery  which  turns 
the  optical  apparatus.  The  windward  bell  is  always 
sounded  during  a  fog;  and  two  strokes,  given  close 
together  every  half  minute,  afford  the  same  dis- 
tinguishing feature  in  the  fog  signal  which  the  flashes 
do  with  the  light. 


294     Cost  of  Eddy  stone  compared  with  Others. 

The  new  Eddystone  Lighthouse  cost  £59,255,  a 
smaller  sum  than  many  other  isolated  lighthouses, 
such  as,  for  instance,  Skerryvore,  Dhu  Heartach,  Wolf 
Rock,  Great  Basses,  Minot's  Ledge,  and  Spectacle 
Reef.  As,  however,  it  is  larger  than  any  previous 
rock  lighthouse,  the  real  cheapness  of  its  construction, 
compared  with  other  similar  structures,  can  only  be  appre- 
ciated by  a  comparison  of  cost  per  cubic  foot.  Judged 
by  this  standard,  the  new  Eddystone  is  the  cheapest 
isolated  lighthouse  hitherto  erected,  its  cost  being  a  little 
less  per  cubic  foot  than  the  Longship's  and  Bishop  Rock, 
less  than  half  the  proportionate  cost  of  the  Bell  Rock,  and 
less  than  one-third  that  of  the  old  Eddystone  Lighthouse. 
The  focal  plane  of  the  old  lighthouse  was  72  feet  above 
high-water ;  whereas  the  focal  plane  of  the  upper  light 
of  the  new  lighthouse  is  133  feet  above  the  same  level, 
and  its  range  over  the  sea  is  17^  miles. 


THE   EIFFEL  TOWER. 

The  gigantic  tower  which  formed  the  prominent 
feature  of  the  Paris  Exhibition  of  1889,  dwarfing  by 
its  unprecedented  height  all  the  other  buildings  of  the 
exhibition,  has  the  shape  of  a  lighthouse  tower  above 
its  second  stage,  and,  moreover,  exhibited  from  its 
summit  during  the  exhibition  a  flashing  tricolour 
electric  light,  which  could  be  seen  for  many  miles 
round  Paris.  In  other  respects,  however,  it  differs 
entirely  from  the  lighthouse  tower  just  described ; 
though  its  foundations  necessitated  much  more  ex- 
tensive underground  operations,  in  the  alluvial  bank 
of  the  Seine,  than  would  be  imagined  by  a  casual 


Tke  High  Edifices  of  the  World.  295 

visitor  passing  under  its  widespread  arches  supporting 
the  first  stage.  Some  high  lighthouse  towers  have, 
indeed,  been  built  of  iron,  as,  for  instance,  the  Roches- 
Douvres  Lighthouse,  on  a  reef  to  the  west  of  the  island 
of  Jersey,  167  feet  high  up  to  the  lantern  gallery ;  but 
the  great  height  of  the  Eiffel  Tower  necessitated  an 
openwork  structure  to  reduce  the  weight,  and  to  offer 
less  surface  to  the  wind. 

High  structures  have  always  been  objects  of  fascin- 
ation to  mankind  from  the  very  earliest  times,  as 
exemplified  by  the  first  recorded  instance  of  a  large 
work  being  the  building  of  the  Tower  of  Babel.  The 
Colossus  of  Rhodes,  a  bronze  statue,  105  feet  high, 
erected  2170  years  ago,  occupied  twelve  years  in 
construction,  and  was  regarded  as  one  of  the  seven 
wonders  of  the  world.  The  pyramids,  however,  of  much 
greater  antiquity,  though  apparently  built  more  with  a 
view  to  great  massiveness  and  durability  than  eleva- 
tion, have  a  much  greater  height.  The  pyramid  of 
Cheops,  with  a  height  of  484  feet,  exceeded  in  height 
all  other  buildings,  with  the  single  exception  of  the 
spire  of  old  St  Paul's1  from  about  1240  to  1561,  till 
the  completion  of  Cologne  Cathedral,  in  1880,  and  the 
erection  of  the  obelisk  of  Washington,  with  heights 
respectively  of  528  and  541  feet,  displaced  it  from  the 
foremost  position,  which  it  had  held  for  the  greater 
part  of  the  thirty  centuries  of  its  existence.  The  idea 
of  a  tower  of  300  metres  (984  feet),  nearly  double 
the  height  of  any  previous  edifice,  appears  not  to  have 
been  quite  novel  when  proposed  by  Mr  Eiffel,  in  1886, 

1  Old  St  Paul's  Cathedral  in  London,  completed  about  1240,  and 
destroyed  in  the  great  fire,  had  a  spire  reaching  a  height  of  520  feet ;  but 
this  spire  was  destroyed  by  lightning  in  1561. 


296  Foundations  of  the  Eiffel  Tower. 

as  an  object  of  special  attraction  for  the  Paris  Exhibi- 
tion of  1889.  Mr  Trevithick,  in  1833,  proposed  the 
erection  of  a  cast-iron  column,  1000  feet  high,  in 
commemoration  of  the  Reform  Bill  of  1832;  it  was  to 
have  a  diameter  of  100  feet  at  the  base,  and  12  feet 
at  the  top;  but  the  death  of  its  designer  the  same  year 
put  an  end  to  the  project.  The  Americans,  also,  at 
the  time  of  the  centenary  of  the  independence  of  the 
United  States,  conceived  the  idea  of  commemorating 
it  by  a  tower  1000  feet  high  ;  but  eventually  they 
contented  themselves  with  the  Washington  Obelisk, 
which,  till  the  erection  of  the  Eiffel  Tower,  was  the 
highest  structure  in  the  world. 

The  tower,  weighing  6500  tons,  and  resting  at  the 
base  on  four  trellis-work  piers,  required  very  solid 
and  secure  foundations ;  and  as  a  great  leverage 
is  exerted  by  the  wind  in  blowing  against  the  upper 
portion,  it  was  essential  to  connect  the  tower  very 
firmly  at  its  base  with  its  foundations.  The  founda- 
tions were  commenced  at  the  beginning  of  1887. 
The  foundations  of  the  two  piers  furthest  from  the 
Seine  could  be  excavated  and  built  up  in  the  open 
air,  as  a  thick  layer  of  gravel  was  met  with  i6£  feet 
below  the  surface,  at  the  level  of  the  ordinary  water 
level  of  the  Seine ;  but  the  foundations  of  the  two 
piers  nearest  the  river  had  to  be  carried  down  double 
this  depth  to  reach  the  gravel,  and  therefore  i6£  feet 
below  the  ordinary  level  of  the  Seine.  These  two 
foundations  were,  accordingly,  excavated  and  laid  by 
the  aid  of  compressed  air,  four  wrought-iron  caissons, 
49  feet  long  and  13  feet  wide,  being  sunk  for  each 
pier  down  to  a  depth  of  33  feet.  The  masonry 
foundations  rest  upon  beds  of  concrete;  and  the  four 


Description  of  the  Eiffel  Tower.  297 

ribs  of  each  of  the  four  pedestals,  converging  in 
pyramid  form  towards  the  first  platform,  are  each 
fastened  to  the  masonry  foundations  by  two  anchor- 
age bolts,  25^-  feet  long  and  4  inches  in  diameter, 
fixed  at  their  lower  ends  to  a  large  anchorage  plate 
embedded  in  the  masonry.  These  bolts,  besides 
fastening  the  pedestals  supporting  the  tower  firmly  to 
their  foundations,  which,  moreover,  is  mainly  accom- 
plished by  the  great  weight  of  the  structure,  were  also 
very  serviceable  in  supporting  the  slanting  pedestals 
during  their  erection.  The  four  pedestals  were  further 
supported  in  their  overhanging  position  by  temporary 
props,  till  they  could  be  connected  and  mutually 
supported  and  strengthened  by  the  girders  spanning 
the  intervals  between  them,  and  supporting  the  first 
platform. 

The  tower  has  been  built  of  a  series  of  main  ribs, 
formed  of  riveted  angle-irons  and  plates,  braced  and 
connected  together  by  a  trellis-work  of  angle-irons, 
connecting  plates,  and  bars.  (See  illustration^  The 
pieces,  though  large,  appear  light  in  comparison  with 
the  size  of  the  whole  structure,  and  form  a  graceful 
network,  adding  beauty  to  the  tower  which,  in  its 
general  outline  above  the  second  platform,  has  an 
artistic  appearance.  The  only  heavy-looking  part  of 
the  edifice  is  the  high  screen  surrounding  the  first 
platform,  necessitated  by  this  part  being  used  as  a 
restaurant.  The  second  platform,  of  much  smaller 
dimensions  than  the  first,  is  borne  on  four  pedestals, 
resting  on  the  lower  pedestals,  but  with  a  smaller 
amount  of  convergence,  and  is  supported  by  straight 
girders  across  the  much  smaller  intervals  between 
the  pedestals,  without  the  embellishment  of  arches, 


298     Construction  and  Cost  of  Eiffel  Tower. 

which,  placed  under  the  lower  platform  as  a  struc- 
tural adornment,  add  nothing  to  the  strength.  The 
actual  tower  starts  from  the  second  platform,  and  is 
surmounted,  above  the  third  platform  and  balcony,  by 
a  campanile,  and  a  lantern  at  the  summit.  The 
work  involved  the  employment  of  2\  million  rivets, 
of  which  600,000  had  to  be  riveted  in  place,  to  connect 
the  several  parts  together.  The  whole  of  the  parts 
were,  as  far  as  possible,  completed  at  the  workshops  \ 
so  that  when  lifted  into  place  by  special  cranes,  the 
junctions  only  had  to  be  completed,  every  piece  hav- 
ing been  so  carefully  fitted  beforehand  as  to  require 
no  further  adjustment.  Most  large  buildings  require 
a  considerable  period  for  their  erection ;  but,  owing 
in  great  measure  to  the  care  exhibited  in  every  detail, 
the  tower  was  completed  from  the  foundations  to  the 
top  in  about  two  and  one-third  years.  The  cost  of 
the  tower  was  about  £200,000. 

In  order  to  regulate,  if  necessary,  the  respective 
heights  of  the  four  lower  pedestals  supporting  the 
structure,  a  hydraulic  press  was  inserted  under  each 
of  the  four  cast-iron  bed-plates  on  which  the  pedestals 
rest,  capable  of  exerting  a  pressure  of  800  tons.  These 
presses,  however,  were  little  used  in  the  course  of  con- 
struction, owing  to  the  accuracy  with  which  the  parts 
were  erected.  The  verticality  of  the  tower  was  tested 
by  angular  measurements  when  the  tower  had  reached 
a  height  of  720  feet,  and  was  found  to  be  exact.  Cast- 
iron  pipes,  connected  with  the  metal  pedestals  at  the 
base  of  the  tower,  have  been  carried  down  to  the  water- 
bearing strata  underneath,  so  as  to  ensure  the  ready 
escape  of  the  electric  fluid  which  may  reach  the  tower. 
In  this  manner  the  tower  forms  an  enormous  lightning 


THE    EIFFEL   TOWER. 

i.  Cologne  Cathedral.     2.  Strasburg  Cathedral.     3.  Salisbury  Cathedral.     4.  Victoria 
Tower,  Houses  of  Parliament.      5.  St.  Paul's  Cathedral,  London.     6.  St.  Peter's,  Rome. 

?.  The  Great  Pyramid.     8.  The  Pantheon,  Paris.     9.  The  Duomo,  Florence.     10.  The 
nvalides,  Paris. 


Eiffel  Tower  compared  with  Highest  Building  s.    299 

conductor,  ensuring  a  large  neighbouring  area  against 
danger  from  lightning. 

The  width  across  the  base  of  the  tower  is  410  feet ; 
and  the  width  of  the  openings  between  the  bottom 
pedestals  is  243  feet.  The  first  platform  is  189  feet 
above  the  ground,  only  27  feet  lower  than  the  top  of 
the  towers  of  the  cathedral  of  Notre  Dame  in  Paris. 
The  second  platform  is  situated  at  an  elevation  of  380 
feet,  which  is  14  feet  higher  than  St  Paul's  Cathedral 
in  London.  The  height  of  the  actual  tower,  rising 
from  the  second  platform,  and  supporting  the  third 
platform,  with  an  intermediate  floor  half  way  up,  is 
526  feet;  so  the  third  platform  is  at  a  height  of  906 
feet  from  the  ground,  more  than  double  the  height  of 
all  but  about  half-a-dozen  of  the  highest  buildings  in 
the  world,  and  within  a  few  feet  of  the  height  which 
would  be  attained  by  Cologne  Cathedral  if  perched 
on  the  summit  of  the  Great  Pyramid.  The  project- 
ing balcony  of  this  platform  is  the  greatest  height  to 
which  the  general  public  are  admitted.  The  campanile, 
however,  with  the  lantern  above,  increases  the  elevation 
of  the  tower  to  its  full  height  of  984  feet  above  the 
ground,  or  1094  feet  above  sea  level.  The  total  height 
of  the  tower  is  therefore  more  than  double  the  height 
of  all  existing  buildings,  with  three  exceptions,  namely, 
the  Washington  Obelisk  and  Cologne  Cathedral,  already 
mentioned,  and  Ulm  Cathedral,  which  was  completed 
in  1890,  having  a  total  height  of  530  feet.  There 
is,  accordingly,  at  the  present  time  no  building  in 
the  world  which  reaches  within  440  feet  of  the  Eiffel 
Tower. 

The  summit  of  the  tower  can  be  reached  by 
staircases,  with  a  total  number  of  1793  steps;  but 


300      Lifts  for  ascending  the  Eiffel  Tower. 

the  ascent  as  far  as  the  balcony  below  the  cam- 
panile can  be  made,  by  hydraulic  lifts,  in  four  stages. 
Three  systems  of  lifts  have  been  adopted  for  this 
purpose,  two  of  them  being  designed  so  as  to  follow 
the  inclination  of  the  pedestals  in  their  journey,  and 
one  of  these  two  systems  being  adapted  for  changing 
the  inclination  in  ascending  to  the  second  platform ; 
and  the  third  system  is  arranged  as  a  vertical 
counterbalanced  lift,  in  two  equal  sections,  to  provide 
communication  between  the  second  and  third  platforms. 
Four  lifts  lead  from  the  ground  to  the  first  platform ; 
and  two  of  these  continue  the  ascent  to  the  second 
platform.  The  ascent  to  the  third  platform  from  the 
second  is  effected  in  two  stages,  by  means  of  two 
counterbalancing  lifts  performing  half  the  journey,  and 
a  change  of  carriage  is  effected  at  the  midway  floor. 
The  two  lifts  leading  only  to  the  first  platform  have 
carriages,  i6|  feet  high,  divided  into  two  floors,  run- 
ning on  wheels  inside  the  pedestals,  and  holding  100 
persons ;  and  they  can  ascend  at  a  speed  of  3 \  feet 
per  second.  The  two  other  lifts,  going  up  to  the 
second  platform,  only  hold  50  passengers  each,  but 
travel  at  double  the  speed  of  the  others.  Like  the 
previous  lifts,  they  are  partially  counterbalanced  to 
diminish  the  force  needed  to  drag  them  up,  the  haul- 
age being  effected  by  six  steel  wire  cables.  In  each 
case  the  lifts  can  descend  empty  by  their  slight  excess 
of  weight  over  the  counterpoise;  and  self-acting  safety 
brakes  arrest  a  too  rapid  descent.  In  the  ascent  from 
the  second  to  the  third  platform,  which  is  accomplished 
by  two  equal  stages  of  263  feet  of  vertical  ascent,  the 
two  lifts,  each  performing  half  the  ascent  alternately, 
work  in  unison,  one  ascending  as  the  other  goes  down, 


Tower  contrastedwithD  our o&  Garabit  Viaducts.  301 

being  connected  by  four  chains  passing  over  pulleys 
at  the  top.  One  of  the  lifts  is  moved  up  and  down 
by  two  hydraulic  presses  at  the  sides,  and  controls  the 
motion  of  the  other ;  and  both  of  the  lifts  travel  along 
vertical  guides  forming  part  of  the  framework  of  the 
tower.  Each  lift  can  hold  about  63  passengers ;  and 
the  journey,  including  the  change  of  lift  midway,  can 
be  effected  in  about  five  minutes. 

The  campanile  at  the  top  is  reserved  for  meteoro- 
logical and  other  scientific  observations ;  and  the 
lantern  contains  an  electric  lamp  with  optical  apparatus 
of  the  first  order.  The  oscillation  at  the  top  of  the 
tower  in  a  gale  has  been  estimated  at  a  maximum 
of  about  6  inches. 

The  tower  has  admirably  answered  the  object  for 
which  it  was  designed,  of  greatly  surpassing  all  other 
erections  in  height,  and  thus  attracting  sightseers,  and 
imparting  novelty  to  the  Paris  Exhibition  of  1889.  Its 
construction  was  also  effected  at  a  comparatively 
moderate  cost,  and  in  a  short  space  of  time,  and  has 
combined  simplicity  with  a  moderate  degree  of  grace- 
fulness. The  tower  has,  moreover,  achieved  a  world- 
celebrity  for  its  designer,  which  the  Douro  and 
Garabit  viaducts  did  not  accomplish,  though  these 
structures  unite  the  simplicity  and  boldness  of  the 
tower  with  far  greater  utility,  and  a  distinctly  greater 
elegance.  The  tower  is  in  fact  the  result  of  the  ex- 
perience gained  in  these  earlier  designs;  and  no 
portion  of  the  construction  of  the  tower  equalled  in 
difficulty  the  erection  of  arches  of  525,  and  541  feet 
span,  across  the  valleys  of  the  Douro  at  Oporto  and 
the  Truyere  at  Garabit,  without  any  scaffolding  or 
intermediate  supports.  The  renown  of  the  tower  is. 


302  Importance  and  Variety  of  Engineering  Works. 

due  to  its  absolutely  unrivalled  height,  the  occasion 
of  its  erection,  and  its  position  in  the  most  popular 
capital  of  the  world ;  but  it  is  unquestionable  that 
the  Garabit  Viaduct,  the  Antwerp  quays,  the  Danube 
and  Mississippi  delta  works,  the  Alpine,  Rocky 
Mountain,  and  Transandine  railways,  the  Severn 
Tunnel,  the  Brooklyn  and  Forth  bridges,  and  several 
other  works,  are  far  greater  engineering  triumphs. 

Concluding  Remarks. — Enough  has  been    said  in  the 
preceding    pages    to    indicate    the    great    influence    the 
works    of    engineers    exercise    over     the     destinies     of 
mankind,  and  how  much  they  conduce  to  the  progress, 
comfort,  and  well-being   of  nations.      The  works,  how- 
ever, described  are   merely   a  few  remarkable   instances 
chosen  out  of  a  great  number  of  very  important  works 
which  engineers  have  carried  out  in  almost  every  part 
of    the    world.      Moreover,    it    is    impossible,    within    a 
limited    space,   to    refer    to    various   other   branches    of 
engineering   science   in  which  the  skill  of  the  engineer 
has    conferred   inestimable  benefits  on  the  human  race. 
It    has    been    shown    how    all    the    various    works    for 
facilitating    locomotion    on    land,    and    affording  access 
from    the    sea    to     ports,    and    by    waterways     to     the 
interior    of    a    country,     are      due     to    the    labours    of 
engineers,  and  how  the  indispensable  water  supplies  for 
large    towns    are    secured    by    their    aid.        Engineers, 
however,    also  provide    for   the  drainage  of  large  towns 
and    districts,   the    mitigation    of    inundations    on    low- 
lying  lands,  the  reclamation  of  lands  from  the  sea,  and 
the  irrigation  of  large  tracts  of  land  in  warm  countries, 
by   which    crops    are    preserved    and    famine    averted  ; 
and    they   carry   out    the    works    for    the    illumination 


Benefits  conferred  on  Mankind  by  Engineers.    303 

of  streets  and  houses  with  gas  and  electricity.  The 
improvements,  also,  of  marine  engines  have  increased 
the  speed  of  vessels,  and  notably  shortened  the  time 
of  transit  across  the  Atlantic,  and  to  different  parts 
of  the  world  ;  whilst  improvements  in  telegraphy  and 
the  laying  of  submarine  cables  enable  communications 
to  be  rapidly  exchanged  between  distant  quarters 
of  the  globe.  Moreover,  the  development  of  most  of 
these  advantages,  like  the  works  described,  have  been 
achieved  within  the  last  fifty  years ;  and  if  engineers 
in  the  future  continue,  as  in  the  last  half  century, 
increasing  and  extending  the  benefits  resulting  from 
their  works,  they  will  justly  be  regarded  as  ranking 
amongst  the  greatest  benefactors  of  mankind. 


INDEX 


ABT  RACK  RAILWAYS,  66-69 !  various,  67 ; 
Transandine,  68  ;  advantages,  68-69. 

AiR-LocK  at  Hudson  River  Tunnel,  90 ;  de- 
scription, 90  ;  in  compressed  air  diving-bell, 
161  ;  for  caissons  at  Antwerp  quays,  183. 

ALEXANDRIA  HARBOUR,  194-195  ;  description, 
194;  section  of  breakwater,  192,  194;  method 
of  construction  of  breakwater,  195  ;  rapid 
construction  of  breakwater,  195. 

ALPINE  RAILWAYS,  26-38,  59-61,  62-66 ;  de- 
scriptions of  principal,  26-38  ;  sections,  30  ; 
compared  with  Rocky  Mountain  railways, 
38-39  ;  along  Mont  Cenis  road,  59-61  ;  up 
mountains,  62-66  ;  considerations  affecting, 
71-73  ;  fresh  routes  proposed,  82-84. 

ALPINE  TUNNELS,  70-84  ;  descriptions  of  prin- 
cipal 70-81  ;  contrasted  with  ordinary  tun- 
nels, 71  ;  proposed,  82-84.  See  MONT  CENIS, 
ST  GOTHAKD,  etc. 

AMSTERDAM  SHIP  CANAL,  240-245  ;  object  and 
route,  240 ;  section,  242  ;  difficult  problems 
involved,  243  ;  description  of  works,  243-245  ; 
land  reclaimed  and  drained,  244,  245  ;  dura- 
tion and  cost  of  works,  245. 

ANDES,  sections  of  railways  over,  30  ;  descrip- 
tions of  railways  across,  46-50,  68. 

ANTWERP,  Port  of,  182-184 ;  early  condition, 
182  ;  development,  182-183  ;  Kattendyk  Dock, 
182  ;  Africa  and  America  docks,  183  ;  con- 
struction of  river  quays,  183-184  ;  increase  of 
trade,  184. 

AQUEDUCT,  swing,  across  Manchester  Ship 
Canal,  249 ;  for  Manchester  Waterworks, 
273-274  ;  from  Thirlmere  to  Manchester,  277 ; 
from  Vyrnwy  to  Liverpool,  281-284. 


ARCHED  BRIDGES,  materials  and  spans  of 
various,  113,  118-119  ;  Douro,  and  Garabit, 
119  ;  St  Louis,  and  Harlem,  121  ;  principles 
of,  127  ;  limits  of  span,  128  ;  bowstring  type, 
128  ;  illustrations,  134;  descriptions  of,  136- 
141. 

ARLBERG  RAILWAY,  37-38  ;  object,  37  ;  de- 
scription, 37-38  ;  elevation  attained,  38  ; 
Trisana  Viaduct  on,  118. 

ARLBERG  TUNNEL,  80-81  ;  rapid  driving  of 
headings.  80  ;  machinery,  strata,  and  con- 
struction, 81  ;  temperature  during  construc- 
tion, 81  ;  cost,  81. 

ATLANTIC  AND  PACIFIC  RAILWAY,  40-41  ; 
route,  40  ;  incomplete  state  of;  40-41. 


B. 


BERLIN  METROPOLITAN  RAILWAY,  route,  and 
description,  16. 

BLASTING  OPERATIONS  AT  HELL  GATE,  162- 
171  ;  description  of  improvement  works,  162- 
171.  See  HELL  GATE,  HALLETT'S  POINT, 
MIDDLE  REEF. 

BLOCK  SYSTEM,  principle  of,  14  ;  adopted  on 
Inner  Circle  Railway,  14. 

BOGIE  CARS,  on  American  railways,  43. 

BOGIE  ENGINES,  New  York  Elevated  Rail- 
way, 19  ;  Fairlie  duplex,  56-58. 

BOULOGNE  HARBOUR,  195-197  ;  importance  of, 
195  ;  enlargement  of,  196  ;  works  carried  out, 
196-197  ;  form  of  breakwater,  192,  197  ;  esti- 
mated cost  of,  197. 

BOWSTRING  GIRDER  BRIDGES,  form  of  arched 
bridges,  128  ;  instances  of,  116-117,  128. 

BRAKES,  continuous,  on  Inner  Circle,  15  ; 
on  Rigi  and  Pilatus  railways,  64,  65-66 

BREAKWATER,  Alexandria,  192,  194-195  ;  Bou- 
logne, 192,  196-197;  Colombo,  192,  198-199; 
Dover,  192,  200-201  ;  Marseilles,  185-186  ; 
Newhaven,  202-203  \  Table  Bay,  192,  193-194. 

BREAKWATERS,  189-205  ;  protecting  Marseilles 
basins,  185-186  ;  various,  189-190  ;  improved 
construction  of,  189,  204-205  ;  arrangements 
of,  for  sheltering  harbours,  190 ;  sections, 
192 ;  different  types,  193,  204-205  ;  descrip- 
tions _of  various,  193-203  ;  difficulties,  and 
experience  needed  in  construction,  203-204. 

BRENNER  RAILWAY,  28-32  ;  object,  28;  section, 
30 ;  description,  31-32  ;  elevation  attained,  31. 

BRIDGE,  Britannia  Tubular,  114-116,  134  ; 
Brooklyn,  120,  127,  132,  143-146,  153  ; 
Channel  (proposed),  156-158 ;  Clifton  Sus- 
pension. 114;  Conway  Tubular,  115; 
Crumlin,  118 ;  Forth,  121,  132,  146-153; 
Garabit,  119,  132,  134,  139-141  ;  Harlem 
River,  21 ;  Hawkesbury,  132,  134,  135-136; 
Hooghly,  132,  134,  141-143;  Hudson  River 
(proposed),  120,  127,  146;  Kentucky  and 
Indiana,  130,  143 ;  Kentucky  River,  118, 
128-129 ;  Kieff  Suspension,  114 ;  Montreal 
Tubular,  115;  Niagara  Cantilever,  129-130, 
134;  Niagara  Suspension,  119-120,  127; 
Portage,  118 ;  Poughkeepsie,  130-131,143; 
St  Louis,  121,  132,  134,  136-139 ;  Saltash, 
116-117,  128;  Sukkur,  131,  153;  Tay,  118  ; 
Tower,  132,  135,  153-156;  Trisana,  118.  See 
also  SPANS  OF  BRIDGES. 


u 


3o6 


Index. 


BRIDGES,  112-158  ;  progress  of  construction, 
112-121  ;  materials  and  spans,  112-114,  120- 
121  ;  arched,  113,  118-119,  I2I»  127-128,  134  ; 
suspension,  113-114,  119-120,  125-127  ;  tubu- 
lar, 114-116,  134;  girder,  114-119,  123-125, 
134  ;  cantilever,  121,  128-131,  134  ;  principles 
of  construction,  121-131  ;  influence  of  in- 
creased spans,  122 ;  descriptions  of  long 
span,  132-158. 

BKIDGEWATER  CANAL,  swing  aqueduct  on, 
249-250  ;  lifts  connecting  it  with  Manchester 
Ship  Canal,  250. 

BRITANNIA  TUBULAR  BRIDGE,  114-115;  cast- 
iron  arch  proposed,  114 ;  tubular  system 
adopted,  114-115  ;  spans  and  headway,  115, 
134  ;  erection,  115. 

BROOKLYN  BRIDGE,  143-146 ;  largest  suspen- 
sion bridge,  120;  dip  of  cables,  127,  144; 
span  compared  with  other  bridges,  134  ;  ob- 
ject, 143  ;  length,  spans,  piers,  and  headway, 
144  ;  suspension  cables,  144  ;  erection,  accom- 
modation, and  cost,  145 ;  compared  with 
Forth  Bridge,  153. 


CALAIS  HARBOUR,  195-196 ;  importance,  195  ; 

improvement       works,       195-196 ;       results 

achieved,  196. 
CANADIAN  PACIFIC  RAILWAY,  44-46  ;  section, 

30 ;   description,    44-46 ;   elevation  attained, 

CANAL,  Amsterdam,  240-245 ;  Bridgewater, 
249-250 ;  Corinth,  242,  253,  264-267 ;  Man- 
chester, 242,  245-252  ;  Nicaragua,  261-264  > 
Panama,  253,  258-261  ;  Suez,  162,  253,  254- 
258. 

CANAL  LIFT,  234-237 ;  object,  234-235 ;  em- 
ployed at  Anderton  and  Fontinettes,  235  ; 
description  of  La  Louviere,  235-237 ;  for 
connecting  Bridgewater  and  Manchester 
canals,  250. 

CANALS,  238-267 ;  lifts  on,  235-237  ;  advantages 
lor  trade,  238-239  ;  descriptions  of  ship  canals, 
240-267  ;  sections,  242  ;  ship  railways  as  sub- 
stitutes, 267-269  ;  importance  and  difficulties 
of,  across  isthmuses,  266-267. 

CANTILEVER  BRIDGES,  definition,  128-129 ; 
principle  of,  129 ;  Niagara  and  Fraser,  129- 
130 ;  advantages  for  building  out,  130 ; 
Kentucky  and  Indiana,  and  Poughkeepsie, 
130-131  ;  Sukkur,  and  Forth,  131  ;  illustra- 
tion, 134;  descriptions  of,  141-143,  146-153. 

CAPITAL  IN  BRITISH  RAILWAYS,  23. 

CENTRAL  PACIFIC  RAILWAY,  39-42,  43.  See 
UNION  PACIFIC  RAILWAY. 

CHANNEL  BRIDGE  (proposed),  156-158  ;  pro- 
posed instead  of  tunnel,  156-157 ;  length, 
piers,  spans,  and  headway,  157  ;  estimated 
weight  and  cost,  157  ;  height  of  structure 
compared  with  high  buildings,  157 ;  com- 
pared with  Channel  Tunnel,  157-158. 

CHANNEL  TUNNEL  (proposed),  109-111 ;  pre- 
liminary investigations,  109-110;  route  and 
length  proposed,  no  ;  gradients  and  drainage 
headings,  in  ;  prospects,  in. 

CHARLOTTENBURG  WEIR,  230-234;  descrip- 
tion, 230;  portion  closed  with  drum  weir, 
230  ;  section  of  drum  weir,  232  ;  description 
of  drum  weir,  233  ;  perfect  control  of  drum 


weir,  233-234  ;  compared  with  weirs  on  River 
Main,  234. 

CHICAGO  RIVKR  TUNNKLS,  86-87. 

CHIGNECTO  SHIP  RAILWAY,  268-269 ;  object, 
and  route,  268 ;  description,  268 ;  advan- 
tages, 268-269. 

COLOMBO  HARBOUR,  197-199;  exposure  of  site, 
197-198;  breakwater,  and  shelter  afforded, 
198  ;  form,  and  construction  of  breakwater, 
192,  198-199  ;  cost  and  revenue,  199  ;  northern 
breakwater  proposed,  199. 

COMPRESSED  AIR,  used  for  constructing  Hud- 
son River  Tunnel,  90-94  ;  in  driving  Thames 
Subway,  109;  for  sinking  caissons  of  St  Louis 
Bridge  piers,  137  ;  in  founding  Brooklyn 
Bridge  piers,  144  ;  for  piers  of  Forth  Bridge, 
150  ;  for  foundations  of  Eiffel  Tower,  296. 

COMPRESSED  AIR  DIVING-BELL,  160-161  ;  for 
removing  submarine  rocks,  160 ;  description, 
160-161  ;  method  of  working,  161. 

CORINTH  CANAL,  264-267  ;  section,  242  ;  object, 
and  ancient  commencement,  264  ;  length,  and 
depth  of  cutting,  264-265  ;  width,  and  slopes, 
265  ;  progress,  and  difficulties  of  works,  265- 
266 ;  prospects,  266  ;  harbour  works  at  en- 
trances, and  bridge  over,  266. 

CURVES,  on  following  railways  :  Arlberg,  38 ; 
Brenner,  31  ;  Canadian  Pacific,  45  ;  Denver, 
43-44  ;  early  main  lines,  25  ;  Elevated,  19 ; 
Fell,  60,  61,  62  ;  Festiniog,  55  ;  Metropolitan, 
8  ;  Mexican,  46 ;  Mont  Cenis,  32  ;  Moun- 
tain, 63,  65,  67  ;  Peruvian,  48  ;  St  Gothard, 
35-36  ;  Semmering,  27  ;  Southern  Pacific,  43  ; 
Union,  or  Central  Pacific,  42. 


D. 


DAM,  across  Lake  Y  for  Amsterdam  Ship 
Canal,  244  ;  Woodhead,  and  Others  in  Long- 
dendale  Valley,  274-275  ;  masonry,  in  Vyrnwy 
Valley,  279-280. 

DANUBE,  River,  216-219  '•>  s'ze  °f  basin,  216- 
217  ;  shallow  outlets  owing  to  delta,  217 
possible  methods  of  improvement,  217-218 
improvement  works  at  Sulina  mouth,  218 
influence  of  works  on  bar  channel,  218-219 
blasting  reefs  at  Iron  Gates,  219. 

DELTA,  plan  of  Mississippi,  208  ;  instances  of 
209  ;  length  and  advance  of  Danube,  217 
area,  and  advance  of  Mississippi,  220. 

DENVER  AND  Rio  GRANDE  RAILWAY,  43-44 
remarkable  features,  43-44 ;  narrow  gauge, 

DETROIT  RIVER  TUNNEL,  88-89 ;  object,  88 
method  of   construction,     88-89 ;     progress, 
difficulties,  and  abandonment,  89. 

DOCKS,  description  of,  along  Thames,  173-177  ", 
hydraulic  machinery  for,  177  ;  difficulties  in 
construction,  177-178  ;  area  of,  in  Port  of 
London,  178 ;  description  of,  in  Port  of 
Liverpool,  178-180;  area  of,  in  Port  of 
Liverpool,  179  ;  extension  of,  at  Antwerp, 
182-183  ;  description  of,  at  Marseilles,  184- 
186  ;  quays  and  jetties  at  New  York,  186- 
188 ;  for  the  Manchester  Ship  Canal,  246- 
250. 

DOVER  HARBOUR,  199-201 ;  original  scheme, 
200  ;  portion  completed,  200 ;  form  and  con- 
struction of  breakwater,  192,  200-201 ;  cost  of 


Index. 


307 


western  breakwater,  201  ;  instance  of  upright 
wall  breakwater,  201. 

DREDGING,  for  removing  shattered  rock  at 
Hell  Gate,  166-167,  I7°  ',  in  Calais  Harbour, 
196;  in  River  Tyne,  208,210,211-212;  amount 
removed  by,  from  Tyne,  211-212  ;  importance 
of,  for  trade,  213  ;  in  River  Maas,  216 ;  for 
construction  ot  Suez  Canal,  256  ;  at  entrance 
to  Suez  Canal,  257. 

DRUM  WEIR,  introduced  on  River  Marne, 
226 ;  across  timber  passes  on  River  Main, 
226,  234 ;  at  Charlottenburg,  230-234  ;  sec- 
tion, 232. 


E. 

EARTH-WAVE,  caused  by  explosion  at  Hell 
Gate,  rate  of  transmission,  170. 

EASTHAM  LOCKS,  at  entrance  to  Manchester 
Ship  Canal,  248. 

EAST  RIVER,  Brooklyn  Bridge  across,  143- 
146,  obstructions  in,  162  ;  quays  along,  187- 
188. 

EDDYSTONE  LIGHTHOUSE,  287-294  ;  site,  287  ; 
history  of  successive  structures,  287-288 ; 
description  of  new,  288-294  ;  rapid  construc- 
tion, 289-292  ;  accommodation,  291  ;  removal 
of  Smeaton's,  and  re-erection  on  Hoe,  292 ; 
old  and  new  lights  exhibited,  292-293  ;  dis- 
tinctive character  of  light,  293  ;  fog  bells, 

293  ;  cost  compared  with  other  lighthouses, 

294  ;    height   of  focal   plane,  and  range   of 
light,  294. 

EIFFEL  TOWER,  294-302 ;  resemblance  to 
lighthouse  tower,  294  ;  high  towers  proposed 
previously,  295-296  ;  foundations,  296-297  ; 
description,  297-298  ;  rapid  erection,  298 ; 
cost,  298  ;  provisions  against  divergence 
and  lightning,  298  ;  dimensions,  299  ;  com- 
pared with  high  buildings,  299 ;  ascent  by 
steps  and  lifts,  299-301  ;  oscillation,  301 ; 
remarks  on,  301-302. 

ELECTRIC  LIGHT,  used  at  Hudson  River 
Tunnel  works,  91  ;  in  compressed  air  diving- 
bell,  161  ;  in  working  chamber  at  Antwerp 
Quay  works,  183  ;  to  light  Manchester  Ship 
Canal  at  night,  250  ;  for  navigation  of  Suez 
Canal  at  night,  258  ;  exhibited  at  St  Cathe- 
rine's Lighthouse,  286;  on  top  of  Eiffel 
Tower,  294,  301. 

ELEVATED  RAILWAY,  NEW  YORK,  16-22.  See 
NEW  YORK  ELEVATED  RAILWAY. 

EXPLOSION,  at  Hallett's  Point,  166  ;  at  Middle 
Reef,  170 ;  of  basin  wall  at  Albert  Dock, 
London,  176. 


F. 


FELL  RAILWAYS,  59-62 ;  Mont  Cenis,  60-61  ; 
Cantagallo,  Brazil,  61-62  ;  New  Zealand,  62. 

FESTINIOG  RAILWAY,  55-56  ;  description,  55- 
56  ;  locomotive,  56-58  ;  passengers,  56. 

FORTH  BRIDGE,  146-153  ;  instance  of  large 
span  steel  bridge,  121  ;  span  compared  with 
other  bridges,  134  ;  schemes  proposed,  and 
site,  146  ;  favourable  situation  for  high  level 
bridge,  147 ;  description,  147-149 ;  length, 
headway,  and  span,  149  ;  sinking  caissons 


for  piers,  150-151  ;  erection  of  superstruc- 
ture, 151  ;  weight  of  steel,  and  cost,  151  ; 
appearance,  151-152  ;  compared  with  other 
structures,  152 ;  compared  with  Brooklyn 
Bridge,  153. 


G. 

GARABIT  VIADUCT,  139-141  ;  example  of  large 
arch,  119  ;  instance  of  erection  by  building 
out,  132,  140 ;  illustration,  134  ;  length, 
height,  and  spans,  139  ;  size  of  arch,  140  ; 
method  of  erection,  140  ;  height  compared 
with  high  edifices,  140, 

GIRDER  BRIDGES,  instances  of,  and  spans, 
114-119  ;  principles  of.  123-124  ;  continuous, 
124-125  ;  illustrations,  134  ;  descriptions  of, 
I15>  JSS-^S- 

GRADIENTS,  on  following  railways:  Arlberg,  38; 
Brenner,  31  ;  Canadian  Pacific,  44  ;  Denver, 
43-44  ;  early  main  lines,  25  ;  Elevated,  19  ; 
Fell,  60,  61,  62  ;  Festiniog,  55  ;  Metropoli- 
tan, 7-8;  Mexican,  46;  Mont  Cenis,  32; 
Northern  and  Southern  Pacific,  42,  43 ; 
Peruvian,  47-50  ;  Rack,  63-68  ;  St  Gothard, 
35-36  ;  Semmering,  27  ;  Simplon,  82  ;  Union, 
or  Central  Pacific,  42. 

GREAT  ST  BERNARD  RAILWAY  (proposed), 
83-84. 


II. 


HALLETT'S  POINT,  162-167  5  plans  and  sec- 
tion, 164  ;  galleries  driven  under,  165  ;  ar- 
rangements for  explosion,  166  ;  method  of 
simultaneous  explosion,  166  ;  removal  of 
shattered  rock,  166-167  >  period  of  works,  and 
cost,  167. 

HARBOUR,  Alexandria,  194-195 ;  Boulogne, 
195-197  ;  Calais,  195-196  ;  Colombo,  197-199  ; 
Dover,  199-201  ;  Marseilles,  184-186 ;  New- 
haven,  201-203  !  Table  Bay,  193-194. 

HARBOURS,  189-202  ;  early  works,  189  ;  various 
recent,  190  ;  size  and  form  dependent  on  site, 
190;  methods  of  sheltering,  190;  descrip- 
tions of,  193-202. 

HAWKESBURY  BRIDGE,  135-136 ;  instance  of 
deep  foundations,  132 ;  illustration,  134 ; 
sinking  caissons  for  piers,  135  ;  floating  out 
girders,  136 ;  accommodation,  length,  and 
cost,  136. 

HEIGHT  OF  BUILDINGS  :  Brooklyn  Bridge 
towers,  144  ;  Cologne  Cathedral,  295  ;  Col- 
ossus of  Rhodes,  295  ;  Eiffel  Tower,  295  ; 
Forth  Bridge  cantilevers,  152  ;  Garabit  Via- 
duct, 140;  Old  St  Paul's  "Cathedral,  295; 
Pyramid  of  Cheops,  295;  Ulm  Cathedral, 
299  ;  Washington  Obelisk,  295. 

HELL  GATE,  NEW  YORK,  162-171  ;  blasting 
operations  for  improving  channel,  162-171  ; 
reason  of  name,  162  ;  earlier  works,  162 ; 
illustrations,  164;  removal  of  Hallett's  Point, 
165-167;  removal  of  Middle  Reef,  167-171. 

HOOGHLY  BRIDGE,  141-143 ;  peculiar  form, 
132,  134,  143 ;  unequal  spans  adopted,  141  ; 
sinking  caissons  for  piers,  141  ;  erection  of 
superstructure,  142  ;  cost,  143. 

HOOSAC  TUNNEL,  73-74. 


3o8 


Index. 


HUDSON  RIVER  BRIDGE  (proposed),  proposed 
span,  and  object,  120  ;  height  proposed  for 
towers,  127 ;  compared  with  Brooklyn  Bridge, 
146. 

HUDSON  RIVER  TUNNEL,  89-94  >  object,  89 ; 
method  of  approach,  90  ;  use  of  compressed 
air,  90,  92 ;  method  of  construction,  and  pro- 
gress, 91,  93 ;  inrush  of  water,  91-92,  93 ; 
sinking  caisson,  92,  93  ;  employment  of  pilot 
tube,  92 ;  shield  for  protecting  face,  93,  94  ; 
stoppage,  and  resumption  of  work,  94. 


I. 


INNER  CIRCLE  RAILWAY,  3-15.  See  METRO- 
POLITAN RAILWAY. 

INLAND  NAVIGATION,  schemes  for  extending, 
238 ;  advantages,  239 ;  revival  in  England, 
239- 


J. 

JETTIES,  at  Port  of  New  York,  187 ;  at  new 
outlet  of  River  Maas,  216  ;  at  Sulina  mouth 
of  Danube,  217-218  ;  at  South  Pass  of  Missis- 
sippi, 221. 


K. 


KENTUCKY  RIVER  BRIDGE,  continuous  girders, 

but  called  cantilevers,  118,  128-129;   spans, 

zi8. 
KENTUCKY  AND  INDIANA  BRIDGE,  form,  and 

spans,  130  ;  central  cantilever,  like  Hooghly 

Bridge,  143. 


LA  LOUVIERE  CANAL  LIFT,  234-237 ;  object 
of  hydraulic  lifts,  234-235  ;  description  and 
working,  235-236 ;  compared  with  Anderton 
Lift,  237;  advantages,  237. 

LAKES  MICHIGAN  AND  ERIE  TUNNELS,  for 
water  supply  of  Chicago,  87  ;  for  water  supply 
of  Cleveland,  87-88. 

LANDING  STAGE,  floating,  at  Liverpool,  181. 

LIGHTHOUSES,  286-294  ;  importance  of,  286  ; 
difficulties  of  construction  on  reefs,  286-287  ; 
instances  of,  287  ;  description  of  Eddystone, 
287-294. 

LIVERPOOL,  Port  of,  178-182  ;  early  condition, 
178-179  ;  great  extension  of  docks,  179  ;  de- 
scription of  docks,  179  ;  areas  of  principal 
docks,  179  ;  access  and  entrances  to  docks, 
180 ;  sluicing  arrangements,  180-181;  float- 
ing landing  stage,  181 ;  importance  of,  181- 
182. 

LOCKS,  Amsterdam  Ship  Canal,  244  ;  Liverpool 
Docks,  180;  Manchester  Ship  Canal,  246- 
249  ;  Millwall  Docks,  174  ;  Nicaragua  Canal 
(contemplated),  262-263  ;  Panama  (proposed), 
260 ;  Poses,  on  Lower  Seine,  229  ;  Tilbury 
Docks,  176,  177  ;  Victoria  and  Albert  Docks, 
174,  175, 

LOCOMOTIVE,  smokeless,  proposed  for  Metro- 
politan, 9  ;  bogie,  on  Elevated  Railway,  19- 
20 ;  tractive  force  of,  on  Semmering,  27-28  ; 


Fairlie,  46,  56-58,  59  ;  gripping  central  rail, 
60-62  ;  Baldwin,  on  Cantagallo  Railway,  61  ; 
Rigi  Railway,  63-64;  Pilatus  Railway,  65- 
66  ;  Abt  system,  67-69  ;  compressed  air,  for 
St  Gothard  Tunnel,  80. 

LONDON,  Port  of,  173-178  ;  early  dock  exten- 
sions, 173;  Victoria  Dock,  173-174;  Mill- 
wall  Docks,  174-175  ;  South  West  India 
Dock,  174-175;  Albert  Dock,  175-176;  Til- 
bury Docks,  176-177  ;  area  of  docks,  and 
extent,  178  ;  importance  of,  181-182. 

LONDON  WATER  SUPPLY,  from  springs  and 
wells,  271  ;  unsatisfactory  condition,  284 ; 
increasing  demand,  285  ;  need  of  control,  285. 


M. 


MAAS,  River,  215-216 ;  peculiarities  of  outlet, 
215-216 ;  shoaling  of  outlet  channels,  216 ; 
new  cut,  training,  and  jetties,  216  ;  improved 
depth,  and  trade,  216. 

MANCHESTER  SHIP  CANAL,  245-252  ;  object, 
245  ;  description,  246-248  ;  accessory  works, 
248-250 ;  accommodation  for  trade,  250 ; 
strata  traversed,  plant,  and  extent  of  works, 
250-251 ;  facilities  for  navigation,  250-251 ; 
advantages,  and  interest  of  undertaking, 
251-252. 

MANCHESTER  WATERWORKS,  273-278  ;  reser- 
voirs in  Longdendale  Valley,  273-276 ;  con- 
veyance of  water  to  Manchester,  274 ; 
description  of  works,  274-275  ;  compensation 
water,  275  ;  separating  weirs,  276 ;  volume, 
and  cost  of  supply,  276  ;  supplemental  supply 
from  Thirlmere,  276-278. 

MARSEILLES,  Port  of,  184-186  ;  early  condition, 
184  ;  sheltered  by  breakwaters,  185  ;  develop- 
ment, 185-186. 

MERSEY  TUNNEL,  94-100 ;  site,  and  object, 
94-97  ;  section,  96  ;  preliminary  works,  and 
shafts,  97  ;  driving  of  drainage  tunnel,  97-98  ; 
construction  of  tunnel,  98  ;  stations,  98-99  ; 
ventilation,  99  ;  length,  and  cost,  99. 

METROPOLITAN  RAILWAY,  3-16  ;  commence- 
ment, 3  ;  extensions,  3,  n,  12  ;  description, 
5-9  ;  connections,  12-13  ;  safety  appliances, 
14-15  ;  cost,  21  ;  for  Paris,  proposed,  15-16  ; 
in  Berlin,  16. 

MEXICAN  RAILWAY,  46  ;  section,  30  ;  descrip- 
tion, 46  ;  Fairlie  engine  used  on,  46. 

MIDDLE  REEF,  East  River,  N.Y.,  167-171; 
plans  and  sections,  164  ;  site,  and  area,  167  ; 
driving  of  galleries  under,  167  ;  preparations 
for  explosion,  167-169  ;  rackarock  for  charges, 
168  ;  arrangements  for  sympathetic  detona- 
tion, 168-169  ;  firing  of  charges,  169-170  ;  rate 
of  transmission  of  shock,  170;  removal  of 
shattered  rock,  171  ;  cost,  170  ;  advantages 
of  work,  170-171. 

MILLWALL  DOCKS,  area,  and  size  of  lock,  174; 
concrete  in  dock  walls,  175. 

MISSISSIPPI  RIVER,  219-223  ;  plan  of  delta, 
208  ;  length,  and  basin,  219-220 ;  delta,  and 
material  brought  down,  220 ;  passes,  and 
shoals,  220  ;  jetty  works  at  South  Pass,  221  ; 
improvement  in  bar  channel,  221  ;  deepening 
at  head  of  pass,  222. 

MOLLENDO   AND  PuNO  RAILWAY,  47  J   Section, 

30  ;  length,  elevation,  and  route,  47. 


Index. 


309 


MONT  BLANC  TUNNEL  (proposed),  83-84. 

MONT  CENIS  RAILWAY,  32-33 ;  description, 
32-33  ;  advantages  of,  33  ;  temporary  Fell, 
60-61. 

MONT  CENIS  TUNNEL,  73-77  ;  method  of  con- 
struction, 74 ;  progress  and  enlargement, 
75  ;  completion,  76  ;  ventilation,  76  ;  tem- 
perature during  construction,  77  ;  cost,  80. 

MONTE  GENEROSO  RAILWAY,  66. 

MOUNT  WASHINGTON  RACK  RAILWAY,  62-63. 

MOVEABLE  WEIRS,  225-234.  See  WEIRS, 
POSES  WEIR,  CHARLOTTENBURG  WEIR. 


N. 

NARROW  GAUGE  RAILWAYS,  54-59  ;  Denver 
and  Rio  Grande,  54-55  ;  Festiniog,  55-56  ; 
various,  58-59;  Fell,  59-62. 

NEWHAVEN  HARBOUR,  201-203  >  site,  and 
prior  condition,  201-202 ;  improvement 
works,  202  ;  line,  length,  and  cost  of  break- 
water, 202  ;  method  of  constructing  break- 
water, 202-203. 

NEW  YORK,  Port  of,  186-188;  advantageous 
position,  186 ;  quay  walls  and  jetties  for 
vessels,  187  ;  extensions  of  quays  and  jetties, 
187-188  ;  large  trade  of,  188. 

NEW  YORK  ELEVATED  RAILWAY,  16-22 ; 
object,  17  ;  description,  17-21 ;  cost,  21  ; 
success  of,  and  passenger  traffic  on,  22. 

NIAGARA  CANTILEVER  BRIDGE,  129-130  ;  de- 
scription, 129-130  ;  elevation  of,  134. 

NIAGARA  SUSPENSION  BRIDGE,  119-120  ;  de- 
scription, 119  ;  reconstruction,  119  ;  used  for 
railway,  119,  120. 

NICARAGUA  CANAL,  261-264 ;  selection  of 
route,  261  ;  commencement  of  works,  261, 
263  ;  description  of  scheme,  262-263  ;  esti- 
mated cost,  263. 

NORTHERN  PACIFIC  RAILWAY,  42-43  ;  route, 
40  ;  description,  42-43. 


O. 


OROYA  RAILWAY,  ^47-50;  section,  30;  de- 
scription, 47-50 ;  switchbacks  introduced, 
48  ;  difficulties  encountered  in  works,  49  ; 
elevation  attained,  50  ;  cost,  54. 


P. 


PACIFIC  RAILWAYS,  38-53  ;  North  American, 
39-46  ;  Mexican,  46  ;  Peruvian,  46-50  ; 
Transandine,  68. 

PANAMA  CANAL,  258-261  ;  section  242  ;  vari- 
ous routes  proposed,  258  ;  length,  depth  of 
cutting,  and  dimensions,  259  ;  progress  of 
works,  and  difficulties,  259-260  ;  plant  em- 
ployed on  works,  260  ;  estimated  cost,  260  ; 
proposed  introduction  of  locks,  260 ;  stoppage 
of  works,  260  ;  preference  given  to  Nicar- 
agua route,  261. 

PARIS  METROPOLITAN  RAILWAY  (proposed), 
15-16. 

PASSENGER  TRAFFIC,  on  Elevated  Railway, 
22  ;  British  Railways,  23-24 ;  United  States 
Railways,  52  ;  Festiniog  Railway,  56. 


PERUVIAN  RAILWAYS,  46-50;  sections,  30; 
Arequipa  to  Puno,  47  ;  Callao  to  Oroya,  47- 
50 ;  cost,  54. 

PILATUS  RAILWAY,  65-66 ;  route,  65  ;  con- 
struction, 65  ;  brakes,  and  speed,  65-66  ; 
self-propelling  carriage,  66. 

PORT,  Antwerp,  182-184  ;  Liverpool,  178-182  ; 
London,  173-178  ;  Marseilles,  184-186  ;  New 
York,  186-188. 

PORTS,  172-188  ;  importance  of,  for  foreign 
trade,  172  ;  recent  development  of  various, 
172;  history  of  some  principal,  173-188. 

POSES  WEIR,  227-230 ;    new  type,   226,   227- 

228  ;    advantages,    228  ;    requirements,   228- 

229  ;  position  and  description,  229  ;  magni- 
tude, 229-230. 

POUGHKEEPSIE  BRIDGE,  form  and  spans,  130- 
131 ;  central  cantilever,  like  Hooghly  Bridge, 
MS- 
PROGRESS  OF  RAILWAYS,  51-53- 


Q. 

QUAYS,  construction  of,  at  Antwerp,  183 ; 
built  on  breakwaters  at  Marseilles,  185  ;  along 
river  frontages  at  New  York,  187  ;  extension 
of,  at  New  York,  187-188. 


R. 


RACKAROCK,  explosive  used  at  Hell  Gate,  168  ; 
composition,  and  advantages,  168  ;  economy 
effected  by  using,  170. 

RACK  RAILWAYS,  62-69.  $ee  RIGI,  PILATUS, 
etc. 

RAILWAY,  Abt  Rack,  66-69  \  Arlberg,  37-38  ; 
Berlin  Metropolitan,  16 ;  Brenner,  28-32 ; 
Canadian  Pacific,  44-46 ;  Chignecto  Ship, 
267-269  ;  Fell,  59-62  ;  Festiniog,  55-58  ;  Lon- 
don Metropolitan,  3-15  ;  Mersey,  94-100 ; 
Mexican,  46;  Mont  Cenis,  32-33;  Narrow 
Gauge,  54-59 ;  New  York  Elevated,  16-22  ; 
Paris  Metropolitan  (proposed),  15-16  ;  Peru- 
vian, 46-50 ;  Pilatus,  65-66 ;  Rigi,  62-65  ; 
St  Gothard,  33-36  ;  Semmering,  26-28  ;  Sim- 
plon  (proposed),  37,  82-83  ;  Transandine,  68  ; 
United  States  Western,  39-44. 

RAILWAY  EXTENSIONS,  in  London,  2-3 ;  of 
Metropolitan,  n,  12;  in  United  Kingdom, 
22-23  5  i°  the  world,  51-53. 

RAILWAY  STATISTICS,  22-23,  5z-53 ;  for  the 
United  Kingdom,  22-23  '•>  progress  of  railways 
in  countries  of  the  world,  51-53. 

RESERVOIRS,  made  for  water  supply  by  dam- 
ming up  streams,  272  ;  in  Longdendale 
Valley,  273-275  ;  Thirlmere,  for  Manchester 
water  supply,  276-278  ;  Vyrnwy  Lake,  for 
Liverpool  water  supply,  279-281.  _ 

RIGI  RAILWAYS,  62-65  5  description  of  first 
line,  63-64  ;  accommodation,  and  speed,  64  ; 
second,  and  third  lines,  64-65. 

RIVER,  Danube,  216-219 ;  Maas,  215-216  ; 
Mississippi,  219-223  ;  Tyne,  210-213  ;  Seine, 
213-215. 

RIVERS,  206-223  ;  contrast  between  tidal  and 
tideless,  206-209  ;  plans  and  sections  of,  208  ; 
object  of  improvement  works,  209-210  ;  de- 
scriptions of  improvement  of  tidal,  210-216  ; 


3io 


Index. 


improvement  of  tideless,  216-223  '>  weirs  on, 
224-234  ;  sources  of  water  supply,  271-272, 
284-285. 

ROCK-BREAKING  RAMS,  161-162 ;  for  excavat- 
ing rock  under  water,  161,  256 ;  method  of 
working,  161-162 ;  rate  of  working,  at  Suez 
Canal,  162. 

ROCKY  MOUNTAINS,  railways  across,  38-46. 


S. 

ST  GOTHAKD  RAILWAY,  33-37  ;  section,  30 ; 
description,  34-36  ;  loops  and  spirals,  35 ; 
influence  on  traffic,  36-37 ;  schemes  in  com- 
petition with,  36-37,  82-84. 

ST  GOTHARD  TUNNEL,  77-80  ;  commencement, 
77  ;  method  of  construction,  77-78  ;  rate  of 
progress,  78  ;  accuracy  of  driving,  79  ;  tem- 
perature of  rock  near  centre,  79  ;  ventilation, 
80;  cost,  80. 

ST  Louis  BRIDGE,  136-139  ;  first  instance  of 
steel  bridge,  121  ;  example  of  building  out, 
132;  illustration,  134;  object,  and  site,  136  ; 
foundations,  137  ;  construction  of  arches  and 
erection,  137-138  ;  accommodation,  and  cost, 
138. 

SALTASH  BRIDGE,  116-117  5  site)  and  form, 
116  ;  spans,  headway,  and  length,  117  ;  ex- 
ample of  bowstring  girder,  128. 

SARNIA  TUNNEL,  109  ;  site,  and  object,  109  ; 
description,  and  mode  of  construction,  109. 

SEINE,  River,  213-215  ;  plan  and  section,  208  ; 
contrast  to  River  Tyne,  213  ;  canalisation  to 
Paris  and  above,  213,  224  ;  area  of  basin, 
213  ;  improvement  by  training  walls,  213-214  ; 
training  works  and  dredging  compared,  214- 
215  ;  weirs  on,  224,  226-230. 

SEMMERING  RAILWAY,  26-28  ;  description,  26- 
27  ;  cost,  27  ;  traction  on,  28. 

SEVERN  TUNNEL,  100-106 ;  section,  96,  101  ; 
object,  and  site,  100  ;  shafts,  and  headings, 
101  ;  flooding  of  works  by  spring,  101-102, 

104  ;  stopping  influx  of  water,  101-103  ;  modi- 
fication of  works,  103  ;  influx  of  river,  103- 

105  ;  shutting  off  spring,  105  ;  pumping,  and 
ventilation,  105  ;  length  of  tunnel,  and  time 
of  traversing,  105-106. 

SHIP  CANALS,  238-267.  See  CANAL,  AMSTER- 
DAM SHIP  CANAL,  etc. 

SHIP  RAILWAYS,  267-269 ;  ancient  inclines  for 
vessels,  267-268  ;  proposed  across  Isthmus  of 
Panama,  268  ;  Chignecto,  described,  268-269. 

SIMPLON  RAILWAY  (proposed),  to  compete 
with  St  Gothard,  37,  83  ;  route  proposed,  82  ; 
prospects,  83  ;  compared  with  other  schemes, 
83-84. 

SIMPLON  TUNNEL  (proposed),  82-83  '>  descrip- 
tion of  scheme,  82 ;  estimated  cost,  82-83  > 
possible  objections,  83. 

SLUICE  GATES,  on  free  rollers  at  Eastham 
Locks,  248  ;  for  discharge  of  Weaver  waters, 
248  ;  for  regulating  flow  in  Manchester  Ship 
Canal,  249. 

SOUTHERN  PACIFIC  RAILWAY,  42-43 ;  route, 
40 ;  description,  42-43. 

SOUTH  WEST  INDIA  DOCK,  174-175  ;  area, 
site,  and  locks,  174 ;  use  of  basin,  174-175  ; 
concrete  in  walls,  175. 

SPANS  OF  BRIDGES,  Alma,  112-113;  Britannia, 
115,  134;  Brooklyn,  120,  144;  Budapest, 


114;  Cha_nnel,  157;  Cincinnati,  117,  118  ; 
Cincinnati  Suspension,  120;  Clifton,  114; 
Coalbrookdale,  113  ;  Coblentz,  119  ;  Connec- 
ticut, 113;  Conway,  115;  Crumlin,  118 : 
Dirschau,  117  ;  Douro,  119  ;  Forth,  121,  149  ; 
Fraser  River,  130;  Freiburg,  114;  Garabit, 
119,  134,  139;  Grosvenor  (Chester),  113; 
Harlem  River,  121  ;  Hawkesbury,  134,  138  ; 
Henderson,  117  ;  Hoogly,  134,  141 ;  Hudson, 
(proposed),  120  ;  Kentucky  and  Indiana,  130  ; 
Kentucky  River,  118  ;  Kieff,  114;  Kuilen- 
berg,  117;  London,  113;  Louisville,  117; 
Mainz,  117  ;  Menai,  113  ;  Monongahela,  120  ; 
Montreal,  115;  Moerdyk,  117;  Niagara 
Cantilever,  129,  134  ;  Niagara  Suspension, 
119;  Passau,  117;  Portage,  118  ;  Pough- 
keepsie,  130-131  ;  St  Louis,  121,  134,  137  ; 
Saltash,  117  ;  Schaffhausen,  113  ;  Southwark, 
113  ;  Sukkur,  131 ;  Sunderland,  113  ;  Tay, 
118  ;  Tower,  154;  Trezzo,  113;  Trisana,  118  ; 
Victoria,  Pimlico,  119;  Wittengen,  113. 

SUBAQUEOUS  TUNNELS,  85-111.    See  TUNNEL. 

SUBMARINE  MINING  AND  BLASTING,  159-171  ; 
ordinary  methods,  159-160;  with  compressed 
air  diving-bell,  160-161  ;  at  Hell  Gate,  New 
York,  162-171. 

SUEZ  CANAL,  254-258  ;  rock-breaking  rams  for 
widening,  162,  256  ;  section,  242  ;  advantages 
of,  253,  254  ;  made  in  ancient  times,  255  ; 
route,  length,  and  size,  255  ;  widening,  255- 
256 ;  description,  and  cost  of  work,  256-257  ; 
large  traffic,  257 ;  improved  facilities  for 
navigation,  258. 

SUKKUR  BRIDGE,  site  and  span,  131 ;  span 
compared  with  other  bridges,  134;  compared 
with  Forth  Bridge,  153. 

SUSPENSION  BRIDGES,  instances  of,  and  spans, 
113-114  ;  for  railway,  119-121  ;  principle  of, 
125-127  ;  contrasted  with  arched  bridges, 
127  ;  description  of,  143-146. 


T. 

TABLE  BAY  HARBOUR,  193-194;  sheltering 
breakwater,  193-194  ;  section  of  breakwater, 
192  ;  progress  of  breakwater,  194. 

THAMES  SUBWAYS,  106-109  !  description  of,  at 
Tower,  106-107  ;  method  of  construction,  107  ; 
compared  with  Thames  Tunnel,  108  ;  for  city 
and  South  London  Railway,  108-109;  descrip- 
tion, and  progress,  108  ;  access  to,  109. 

THAMES  TUNNEL,  used  by  East  London  Rail- 
way, 2-3,  86  ;  description,  and  cost,  86. 

THIRLMERE  WATER  SUPPLY,  276-278  ;  selected 
for  Manchester,  276  ;  description  of  scheme, 
277  ;  volume  available,  277  ;  estimated  cost, 
277-278. 

TILBURY  DOCKS,  176-177  ;  object,  site,  and 
dimensions,  176  ;  tidal  basin,  and  lock,  176- 
177  ;  foundations,  and  walls,  177. 

TOWER  BRIDGE,  153-156  ;  example  of  draw- 
bridge, 132,  154-155  ;  crossing  Thames  below 
London  Biidge,  135,  153-154  ;  river  piers, 
and  spans,  154  ;  description,  154-155  ;  foun- 
dations for  piers,  155-156  ;  length,  and  esti- 
mated cost,  156;  peculiar  features,  and 
importance,  156. 

TRANSANDINE  RAILWAY,  68  ;  elevation  at- 
tained, 68  ;  steep  inclines  worked  by  Abt 
locomotives,  68  ;  variety  of  gauge,  68. 


Index. 


TUBULAR  BRIDGES,  Britannia,  114-115,  134 ; 
Conway,  and  Montreal,  115. 

TUNNEL,  Arlberg,  80-81  ;  Channel  (proposed), 
109-111  ;  Chicago  River,  86-87  ;  Detroit 
River,  88-89  '>  Great  St  Bernard  (prc  ->osed), 
84  ;  Hudson  River,  89-94  ;  Mersey,  94-100 ; 
Michigan,  and  Erie  Lake,  87 ;  Mont  Blanc 
(proposed),  84  ;  Mont  Cenis,  73-77  ;  St 
Gothard,  77-80  ;  Sarnia,  109  ;  Severn,  100- 
106 ;  Simplon  (proposed),  82-83;  Thames, 
86  ;  Tower,  and  another  under  Thames, 
106-109. 

TUNNELS,  Metropolitan  Railway,  5  ;  Semmer- 
ing  Railway,  26-27  '•>  spiral,  35,  43  ;  lengths, 
26,  70-71,  74,  76,  77,  80,  86,  o_9,  108,  109, 
no ;  difficulties  of  construction,  70-71 ; 
Alpine,  70-84  ;  subaqueous,  85-111. 

TYNE,  River,  210-213  ;  plan  and  section,  208  ; 
early  works,  210 ;  breakwaters  at  mouth, 
210-211  ;  dredging  operations,  211-212;  im- 
provements effected,  212. 


UNDERGROUND  RAILWAY,   description,   3-15  ; 

proposed  for  Paris,  16.     See  METROPOLITAN 

RAILWAY. 
UNION  OR  CENTRAL  PACIFIC  RAILWAY,  39- 

42  ;  section,  30  ;  route,  40  ;   description,  41- 

42  ;  elevation  attained,  40. 
UNITED  STATES  WESTERN  RAILWAYS,  39-44  ; 

Pacific     lines,     39-40  ;     Union     or     Central 


Pacific,  41-42,  43  ;  Northern  Pacific,  42-43  ; 
Pacific,   42-43  :    Denver  and  Rio 


Southern 


Grande,  43-44. 
UPRIGHT  WALL  BREAKWATER,  advantages 
of  type,  193  ;  adopted  at  Dover,  200-201  ; 
constructed  at  Newhaven,  203 ;  improve- 
ments in,  204-205. 


V. 


VENTILATION,  Metropolitan  Railway,  9-11 ; 
Mont  Cenis  Tunnel,  76  ;  St  Gothard  Tunnel, 
80 ;  Mersey  Tunnel,  99  ;  Severn  Tunnel, 
105. 

VIADUCT,  Crumlin,  118  ;  Garabit,  119,  134, 
139-141  ;  Portage,  118  ;  Trisana,  118. 

VICTORIA  AND  ALBERT  DOCKS,  LONDON,  174- 
I75>  175-176 ;  site,  dimensions,  and  area, 
T73>  *75  »  basins  and  locks,  173-174,  175 ; 
peculiar  graving  docks,  174 ;  connecting 
new  lock  with  basin,  176. 

VYRNWY  WATER  SUPPLY,  278-284;  for  Liver- 
pool, 278  ;  origin,  278-279 ;  description  of 
reservoir  dam,  279-280 ;  lake  forming  reser- 
voir, 280-281  ;  supply  and  straining  tower, 
281  ;  conveyance  to  Liverpool,  281-283  ; 
balancing  reservoirs,  and  water  tower,  283- 
284;  volume,  and  estimated  cost,  284. 


W. 


WATER  SUPPLY,  270-285;  importance  of,  270; 
sources,  and  respective  advantages,  271-273  ; 
Manchester  waterworks,  273-276  ;  from  Thirl- 
mere,  for  Manchester,  276-278 ;  Vyrnwy, 
for  Liverpool,  278-284  ;  London,  284-285. 

WEAVER,  River,  Manchester  Ship  Canal  pass- 
ing in  front  of,  248  ;  sluice  gates  for  regulat- 
ing flow  of,  248. 

WEIR,  Charlottenburg,  230-234  ;  Port  Villez, 
227  ;  Poses,  227-230  ;  Suresnes,  227. 

WEIRS,  224-234  ;  object  of,  224-225  ;  moveable, 
225-234 ;  needle,  225-226 ;  shutter,  226 ; 
hinged  frame,  226,  227-230 ;  improvement  of 
Seine  by,  230;  drum,  226,  230-234. 


THE  END. 


COLSTON  AND  COMPANY,  PRINTERS,  EDINBURGH. 


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